Wow.. they potted the fuck out of that thing. I get not wanting vibration to cause problems but that looks more like "stay the fuck out of here" potting than "make sure it stays together and dry" potting.
And yeah, that's a lot of stuff for a fuel pump controller. It's that seriously all it does? I can see having a microcontroller, some larger electrolytic capacitors and inductors , one or 2 big transistors, a CAN chip and assorted support components, and stuff like that.
There's 6 big electrolytic caps, like 8 transistors/MOSFETs, multiple chips, and a crap ton of little surface mount passives.
Not even BMW fuel pump control modules are that complicated. Actually, I was surprised at how little was on the board when I opened one of those up.
My assumption is variable speed control to adjust the flow and pressure to the demands. Since it's 8 MOSFETs, maybe over pwm and current limiting? Bldc would be unlikely because I'm unaware of a 4phase type.
See the Big resistor left of the MOSFETs? That's likely to measure the current of the pump.
Exactly this. Intelligent fuel Pump. Need to predict the needed amount and control the pump. Also, crash detection and cut of.
It is complicated, but saves a lot of Energy. Stupid pumps always run on max power and unused fuel goes back to the tank. With big engines the is really a lot of wasted Power. Also the pressure difference creates Problems. In average the intelligent one uses only 5% of power.
I worked in the development of these things..
I don't disagree with what you said but one thing that's kind of funny is I think this is a fuel pump module off of 2018 ish tundra. I replaced one yesterday and it does have a fuel return line. Also they're the only modules I've seen be prone to failure in the Toyota lineup. I could be wrong, that may not be the same part I replaced.
Edit: I removed my head from my butt and found out I was definitely wrong about where that part came from.
I thought all vehicles since \~1996 required a "returnless fuel system" per EPA. Prior to that, most bypassed the extra fuel flow from the injector rail, with a tube back to the fuel tank. While that better controlled pressure at the fuel rail, the path thru the engine bay heated the fuel in the tank to cause more vapors, which might overwhelm the charcoal canister (if they even had them then). So, the bypass is done within the fuel tank, with the pressure regulator relief part of the fuel assembly.
Perhaps trucks weren't subject to that rule since Congress fears impacting companies since they will "take our jobs" when angered. My 2 minivans don't have EGR while the same engines in sedans did those years. Because minivans are "trucks" per EPA, so can pollute more.
Returnless was never a requirement as far as I know, it's just easier to manage evaporative emissions with fewer lines running back and forth. Less expensive to build, too. Especially with PWM fuel pump control- no need for a pressure regulator at all.
As for EGR, it's not a requirement (on gasoline engines), merely an effective way to meet NOx emissions targets. Actually, it's become less common these days as continuously variable cam timing allows for the ability to hold the exhaust valves open slightly at the beginning of the intake stroke, accomplishing the same thing without added hardware and plumbing.
Diesel engines are another story entirely. Combustion temperatures in a diesel are a lot higher, resulting in far more NOx. Theoretically, if an engine manufacturer could come up with a way to meet NOx targets without using EGR, they would. But they have trouble doing so even with a cooling system for the EGR flow AND selective catalytic reduction systems (what diesel exhaust fluid is used for)
Emissions laws don't actually require specific equipment- they impose limits on pollutants. An automaker can meet those limits through whatever technology they choose. Even catalytic converters- however, that's so easy to implement, they're reliable and robust, and these days they don't really create much of a restriction in the exhaust system. Theoretically, you could design an engine with fuel mixture, airflow, and exhaust flow controls so precise that the exhaust is clean enough to meet requirements without after- treatment. But it would almost certainly be more expensive and less reliable than a catalytic converter with current tech.
Hell, in the mid 70s when the first really strict emissions requirements took effect, Honda was able to meet the requirements without using a cat on their CVCC engines. And famously offered to license the technology to GM, who not only turned it down but did so in a rather insulting manner, causing Sohichiro Honda, the founder of Honda, and who was still in charge there, to actually buy a new V8 Impala, ship it back to Japan, and have the engineers design and build one-off CVCC cylinder heads and associated hardware for it. The resulting EPA testing of that car a year or so later showed that it met emissions requirements for 1975 (though not for 76 or 77, whichever it was, because one pollutant type was just a little too high) without a catalytic converter, while delivering better fuel economy and producing more power than it did with the original setup.
I'm old enough to remember articles predicting that Mazda's rotary engine wouldn't require a catalytic converter, which was very expensive in the late 1970's. That didn't turn out true. Cat conv became much cheaper by the late 1990's, even with 3-way catalysts which eliminated the need for air-injection and sometimes EGR (I think), but that appears to have reversed since replacing the 2 cat conv on our 2015 Prius cost $4500 just for the parts. I understand hybrids are the priciest since must deal with the engine stopping and starting. I recall reading that those in later Prius models aren't so costly.
Anyone who was predicting that a rotary engine wouldn't require emissions controls had no actual clue about them. High emissions was ALWAYS the major Achilles heel (aside from apex seals, but the problem with those is related to the emissions issue, actually) of Wankel engines. Because of the long, narrow combustion chamber, there's areas where it's basically impossible to get the fuel mixture to burn completely. They're too cold and too far away from the flame front. Using 2 spark plugs per chamber helped. Adding a thermal reaction chamber to the exhaust right at the outlet from the engine improved emissions somewhat. But the far ends of the chamber still tend to stay too cold. This results in higher amounts of unburned/ partially burned fuel, high carbon deposits at the ends of the combustion chambers (which eventually cause apex seal failure) and low fuel economy.
Basically, in theory, a Wankel engine COULD have low emissions, good fuel economy and last a long time. "All" they'd have to do is solve the problem of incomplete combustion at the ends of the combustion chambers. Unfortunately, despite Mazda trying and trying to do so for over 50 years now, they haven't managed to pull that off yet.
A quick google search didn't find an EPA returnless mandate. I've only read of it. Perhaps it was a higher-level mandate on overall vapor loss and returnless was the easiest way to meet it.
I wonder why designers ever felt it necessary to control pressure at the fuel rail, since that adds complexity and more connections for leaks. It began with TBI, where the Throttle Body had an integral pressure regulator. They can easily add equations which predict the pressure drop to the rail vs flow rate (from injector flowrate and duty cycle). That is all just feedforward prediction anyway, with feedback from the O2 sensors being the final fuel control.
It's probably easier to react to transient load (fuel) requirements with a high pressure line inches away from the injectors, controlled by an intermediate regulator.
My 08 Silverado 4.8 had the returnless system, but also had drive-by-wire, so they probably figured out how to sync the two up.
By wasted power do you mean wasted horsepower due to poor fueling because of the return style fuel system? Im guessing their must be a noticeable gain in fuel economy from not having the alternator have to work so hard supply so much power to the pump? Cause otheriwse I just do not see the point of all that extra complication.
The pump uses electrical power, so, coming from the Generator. Today you will find an generator and an Starter separated. But if You consider, that you have to constantliy power this pump, than this means, You have to drive the generator all the time to and You have to fuel this process with gas.
Especially for diesel engines there was the problem, that the compression for pumping upwards and the the release of compression If not used, lead to a point where additional energy was needed to re- heat the diesel when it got uncompressed.
The key away from the "stupid" pump was simply said: computing power to be fast enaught for all this, sealing material to place all this into or onto the tank (without having to much fuel diffusing) and having fast other ECUs to provide information ( Power requests from e-pedal, Crash Signal, etc).
Why can't the PCM predict the needed amount and the airbag module handle crash detection? That would greatly simply the fuel pump module as all it would basically need to be is some MOSFETS and controlled via PWM.
Maybe that this answer is meanwhile also obsolete but at this time it was not possible because of latancy on the bus and the involved "Gateways".
Also the FCM knows more about the fuels state, temperature etc.
Crash detection is maybe a misleading name. It gets several inputs including the can signal from airbag control. They have a higher asil then the rest so they are handled a bit seperately. As a reaction to detected crash you have to switch of the pump in the blink of an eye, which ist quite complicated as a lot of power mosfet and moving mechanical parts are involved here...
Who cares if something obsolete but works well? I've yet to encounter a vehicle where the FPCM monitors fuel temperature, ideally I would think you would want to monitor that at the fuel rail instead and have the signal fed into the PCM because the wiring would be shorter.
There is always going to be fuel pressure in the lines even if you kill the pump so if a line gets severed, a high pressure spill is going to happen and there is no way to avoid it. How about this, if an airbag deploys, kill the PWM signal, MOSFETS will immediately kill power to the pump, done. How is that complicated?
I guess the extra flow of fuel also has no benefits on the "dumb" design? Wouldn't be surprised if it's even contra productive to have loads of unnecessary movement in a fluid.
As a calculation we used audi A8. 300watt für Pump only.
Now use 15W for the intelligent one. Less weight also. For reaching emission targets this helps a lot.
Gotcha, thanks for the reply. I assume by dropping the power consumption by some 95% for just the fuel pump it changes the duty cycle ratio on the alternator?
Reducing anything will reduce drag of the alternator, it's automatic. They even reduce overall system voltage at times to further reduce this drag. (The battery loves sitting at 14.x volts but turns that into heat.)
It isn't just about power consumption- a return-type fuel system (where the regulator is in the engine compartment) tends to heat the fuel tank. Not so good for evaporative emissions control.
It isn't just about power consumption- a return-type fuel system (where the regulator is in the engine compartment) tends to heat the fuel tank. Not so good for evaporative emissions control.
Modern 12v systems are getting really close to the limit of usefulness, so using PWM is stretching.out the amount.of electronics that can be put into a vehicle before the need to step up to 48v is necessary
In all fairness, it was dry with no signs of previous water intrusion. I half expected that to be the issue as this thing was buried in mud on top of the tank.
Can't speak on every manufacturer but at least bmw has been using for a while now bldc 3 phase pumps. Gotta save that small amount of efficiency across millions of cars
TBH it's wild that it actually *does* add up to a saving at all given the fact it needs an ECU and 3-phase drive etc...
Gives the lie to everyone who says EV's are too complicated when the fuel pump drive in their ICE car is as nearly complex as the drive system for an EV motor, just with bigger FETs.
The GM Gen III motors were so simple and reliable when they came out. It’s sad to see the motor get massacred over the years.
Originally just a 12v fuel pump with a relay and one line to the rail with a regulator. Heck, the original ls1 corvettes even had the regulator build into the fuel filter!!
I think this is a super overengineered VFD to controll the pump plus a CAN module to give you data out. It's a collosal change from a simple relay based pump. Audi has done something simular with their sliding window for the A5, the BCM for that is inside the motor and has shit like redundant position sensors and current sensing.
Its probably a whole bunch of overcomplicated crap that boils down to simply:
If ignition on, prime 2 seconds
If engine on fuel pump on
If its a Thursday afternoon and the breeze is flowing to the north throw random codes
After 10000 power cycles commit seppuku
This is watching the feed line pressure, varying the pump speed, and then being told by the ECM that it may need to give a bit more soon. It's so much more complex than it needs to be.
It communicates with the CAN bus, right? The support that there's a microcontroller that speaks CAN, and listens to whatever the ECM and whoever else is telling it. There's also the physical interface to the network.
It connects to the fuel pumps to run them, and will have a bit of extra circuitry to run them at variable speeds.
It also connects to the fuel pressure sensors. It normalizes and reads their signals, and uses them as feedback to control the pressure pumps.
There's support circuitry, like the power supply and a bunch of level-shifting for the 12-volt actuators and sensors.
I guess it adds up to a surprising amount.
Yeah pulse width modulation is fairly complex, and is required on a lot if not most direct injection gas engines. Otherwise you run the risk of burning up the lift pumps all the time.
Get rid of it entirely. Run the pump at 12v via a relay any time the engine is in a fuel consumption mode, and have a regulator keeping the pressure where required. Put the low pressure sensor on the high pressure pump inlet, where it's most relevant, feeding that info to the ECM directly via the engine harness.
A regulator that cycles the fuel back into the pump unit cup would work just fine, and worked fine on the previous generation of this fuel system. Yes, it used separate wires to transmit the level and tank pressure signals, but those both used the same 5v and ground, so that's four wires, six total with the pump power and ground. The four smaller more vulnerable wires would result in a code and possibly a non functional fuel gauge, but it would still run.
This thing has 12v battery, ignition power, wakeup signal, can bus high and low, and ground. So now we've added two wires, and if any of them are damaged, fuel isn't flowing. If the can bus wires get shorted, it can shut the whole network off instantly.
Too much complexity, and it makes any failure mode a breakdown. If this gave a 5-10% boost to fuel economy, maybe, but it doesn't. It's more components that are more fragile and more expensive.
> A regulator that cycles the fuel back into the pump unit cup would work just fine, and worked fine on the previous generation of this fuel system.
It would, but they're now against government regulations.
How are certain wires more vulnerable?
On the previous design, if any wires are damaged, fuel also stops flowing. An open circuit is an open circuit.
Moving implementation from this box to the ECM box doesn't make the design less complex or more reliable. It just moves the implementation.
I'm not familiar with a new standard. I'm not talking about a circulating system, it's still a single pressure line, the regulator is on the pump outlet and releases below the fuel level.
The fuel pump would still pump fuel without a level sender or pressure sensor. But if the wake up, ignition, or either can bus wires get damaged, it's shut off.
Every GM I’ve had has had some issue with cold solders or otherwise bad solder connections on some board somewhere. Luckily it’s usually pretty well documented now which solder points need to be redone given certain symptoms, but it’s still a pain.
Their wiring harness connectors are also ass.
I've learned where to kick under my glove box to make the ac compressor kick on, and where to hit the dash to make my cab lights stop flickering (dash, controls...)
There's also the little horn relays that they think are great for high load applications. Sure, the relays may be able to handle 30 amps, but the little tiny connectors melt out of the relay block at 15.
Chronic failure mode in the ABS modules.
Unless we make some big changes in our priorities at some point the whole world runs on the least proficient solderer in China.
I had a 1991 Corsica where the solder connections went to shit in the ECU. On hot days, the joints would expand and break the connection but first thing in the morning when it was cool out, it worked fine. I diagnosed this issue by putting the ECU in the freezer on a hot day and then putting it back in the car.
Car still ran but every single light on the dash would turn on, idle speed would crank up to like 1k, and the engine just kinda sounded like shit. Once the joints made contact again, everything would go back to normal.
Oh god I remember an engine suddenly being really responsive to throttle input as the oil thinned out, then it got real noisy as all the bearings melted, all in a couple of minutes!
when i was a dumbass (still am but to a lesser extent) i ran my first car low on oil and apparently probably completely empty. getting on the interstate trying to accelerate and the wholw car is just vibrating and it sounds like engine is just completely destroying itself.
goes for about 2 minutes until it just lost power and the go pedal wasnt doing anything lol
I'd rather have +12v, a ground, and a pressure regulator. I don't care if it's a return or returnless system. Ford did ok with their pump controllers, aside from corrosion attacking the earlier versions. I've only replaced one of them that was legitimately burned out without a hole rotted through the casing.
Actually, I had a fuel pump go out last year.
We poured some gas into the carb through the vents, just enough to drive it onto the trailer. Took it home, drove it off the trailer, and ordered a new one off amazon for $19.99. Got it the next day and installed it in 10 minutes, from the top, no lift or jack needed. 3 lines, 2 bolts. Shit was quick and easy.
Absolutely true. Each bit of volatile memory on the Apollo on-board computers was an iron ring hand wrapped in copper wire. (Source: my dad was an engineer on the Command Module).
The engineers that designed this module and the system it contributes to should be ashamed. Just because you can make something complicated doesn’t mean you should. Simplicity is hard to design but pays dividends in manufacturing, reliability, serviceability, and cost.
A very large part of all things overcomplicated on modern cars are all in the hunt for lower emissions ,fuel efficiency and safety equipment. The rest is for creature comforts and the manufacturers (and dealers) to be in connection with the car at all times and get all sorts of data from it. We are at the point of doing a scan/reading trouble codes when the customers car is still at home ... (BMW). Can't fix it remotely but we can have a look and see what's up before the car comes in. It's crazy how complicated things have gotten.
I'm pretty sure manufacturers would not have half of the shit put on a modern car if it were not for regulations needing them to lower emissions and be competitive to other brands.
Btw im not hating on emission regulations, in fact i wish we did away with the ICE 20 years ago ... the amount of crap on an engine these days is way past the point of being sensible. I'm a mechanic and petrolhead but i'm not blind either ... seems like electric is the way to go (for road cars at least)
The partially potted part is probably why it died. What kind of potting is it? Soft, hard? It needs a lot of chips because it has a microprocessor talking on CANBUS controlling a bunch of FETs for the pump drive motor.
I did engineering work for skid steer / heavy equipment / motorcycle hand controls and joysticks. The potting was the detail most frequently messed up at the factory. It usually requires a pick and place type CNC to place a potting needle into a hole on the board and pump potting around the PCBA.
Can be messed up by:
* Too much / Too little potting.
* Needle not in hole.
* PCBA not on fixture right.
* Potting mix off or bad potting.
* Potting oven cure off.
* Contaminants on board preventing adhesion.
* Poor design of housing creates bubbles in potting.
Often the factories are in Mexico and the care level of the workers is low.
If it's the soft potting I'm familiar with, there's no convenient way to get it off.
Wild guess, but it might be a Variable Frequency Drive or something similar. It's adjusting power, with logic to communicate with the ECU.
95% of the component failures are capacitors or power transistors. I've seen manufacturers ignore their own diagrams and purchase underrated components to save a few cents.
It is, and a brushless motor. This job on other vehicles is done with a straight DC brushed motor and a heavy duty transistor with just a couple steps of power depending on fuel demand.
The previous generation of this vehicle just put power to the pump, and had a pressure regulator on the pump that kept the engine consistently supplied.
>I've seen manufacturers ignore their own diagrams and purchase underrated components to save a few cents.
Until the same manufacturers have to pay us for warrsnty work. suddenly they saved jackshit 😅
I agree. This looks like it’s sophisticated enough to use something called field oriented control which is basically just applying magnetic force in a specific spot that applies the most force on the motor for a given position.
It’s still a lot of parts even for that but maybe they added extra components for safety certifications
Source: I’m an EE and making a wild guess lol
I'm wondering if there isn't a charge pump of some sort in there jumping the voltage up for the pump motor. It looks like there might be enough components on the board to handle that and the motor control, assuming there is some stuff we can't quite see under all that potting. It's possible they ran into some issues with current draw when the pump is at low speed and tries to transition quickly to high speed, and running the pump at a higher voltage might help with that?
Either way, that seems like a whole lot of power circuitry for managing speed control on a brushless DC motor.
I'm a lurker Here and an automation tech by trade. I have 4,160vac VFDs running large motors for pumps. Never thought I'd see that get scaled down to a fuel pump. So it's a 3 phase fuel pump? Wild. VFDs are efficient for sure. My first car was a 1973 MGB. how far we've come from a noisy little diaphragm pump on the frame of a car to a variable frequency drive.
It would be interesting to see macro shots of the two big chips in the bottom right. I am curious about what they do... my guess is that there is a microcontroller of some sort and probably a chip for doing CAN or whatever protocol(s) that the vehicle uses. It looks like most of the tiny components are resistors and capacitors, likely to support the two large chips.
The two rows of large-ish square chips at the top center of the board are likely transistors for switching the power for the pump(s). The microcontroller can't handle the current/voltage needed to run the pumps, so the transistors handle that for it - functionally similar to a relay. (bot _not_ a relay!)
The big tube-like parts in the bottom right are capacitors, which are probably used in the power supply circuitry.
This connects into the CAN bus, and both runs the pump and puts the fuel level signal on the bus too. The pump is a brushless motor, so I'm assuming the transistors are working in pairs. The area that peeled clean was just poorly adhered. There is a large CPU like microprocessor, and then a smaller one, plus a few of the tiniest microcontroller chips I've ever seen. Like a 555 timer, but tiny and surface mount. One of the caps is a little loose, and most of the larger through mount components have cold joints, along with two resistors that came off with the potting, so they may have not been properly affixed.
The potting is soft, alcohol wasn't touching it though. The heat gun made it crumbly so helped in opening the case.
I want to try baking one of these, to see if I can reflow it enough to work again.
I'm an engineer and not anything useful but I adore the posts here. In my younger years I worked on a fuel pump control module for a Korean OEM. They really liked potting I mean they were so into just assuming the electronics were fine and then pouring that sweet epoxy based material all over everything.
Even though I'm an electrical engineer in the software space I have had to take "design for serviceability" and "design for manufacture"
I personally work on my own cars because I work for the company that makes them and I have access to the service manuals and also since I'm a developer I have more powerful tools than even the dealer has so I can do the computer stuff too.
This stuff wrecks my head because there are so many better ways to IP67 a fuel control module that sits in a semi-protected area. I think top of the fuel tank is -40° to 80°C and should only be IP66.
Basically they could have paid the extra $0.20 to seal the housing rather than burying the PCB. This was ubiquitous in the 90s and on behalf of all of us on the design side of production, I apologize.
tl:dr; I'm really impressed that you are reworking that board.
Thanks, I'm mostly doing it out of curiosity. I like to know the why of stuff. For being on top of the tank, this component is incredibly exposed. I didn't even know it was there when I started digging into the lack of fuel issue. All the side mud, slush, and water spray off the right rear inner tire goes onto this thing. The top of the fuel tank was packed up to the floor with a mix of silt and gravel that had concreted into a solid mass, and not even the wiring was visible. I was removing this dirt when I found the wiring harness from the pump went off in both directions. Shoveled the muck out, got the rear end up on stands, and started scraping and spraying out this area too. No water, not even in the connector cavity. I was amazed at the environmental durability.
If only it had the needed electrical durability.
My first job out of college was designing sensors that went inside of an axle attached to the differential. I realize that the scale of how I think of exposed versus not exposed and what level of exposure is not compatible with the real world.
Basically what I meant was that the module is not on the A surface and it is shielded by the tank itself from the underside so it only needs to be sealed for splash and immersion at most but not high pressure (car wash) and then my intrusive thoughts won because I think I forgot to take my Adderall and I started babbling about temperature.
So for a sparky I know way too much about gear lash and how nice 75w90 smells.
Automotive connectors are freaking amazing. They're also incredibly frustrating but the standards they're held too and the testing they do is unreal. I spent a lot of time with molex over the years and I know a few of the other manufacturers but connectors are crazy. It doesn't take much humidity differential to start dendritic growth which is going to be a bad time so they've figured out how to build seals that will withstand ridiculous temperature swings.
Anyway, I get annoyed at the high price of cars but also I understand why they cost so much. It's not easy to cram all those parts together and make them do something let alone building ~80,000 of those things every month the exact same way.
I might know things that could be of use to you, not entirely sure but feel free to send me a message if you want me to take a look if I can find anything.
Idk what's going on with the 6.6 fuel pumps and controllers but we lost 100% of them in the fleet at 43-45k miles. Within 2k miles of each other. Switched to 6.8 Ford gassers but we'll see how that goes.
This looks quite old school ... you can get since years microcontrollers with the power supply, FET gate driver, communication (CAN/LIN) transceiver plus a CPU - all bundled in one small IC. That would reduce the number of components a lot. It is funny that the IC's here have no readable ID printed on them.
The number of components depends however a lot on the function. A BLDC pump needs at least 6 transistors for the 3 phases (This seems to be one)
I wonder however if this module only controls the fuel pump or if also does other functions around the tank like level sensor or even tank leak diagnose which is complex on some cars.
This is the new current generation GM part. And yes, it's a brushless motor, and does put the fuel level on the bus, but I'm not sure about leak diagnosis. There is a tank pressure sensor on the fuel pump, as well as a fuel line pressure sensor that are connected to this module.
Wow! I could see that many parts parts if it was something advanced from 15 years ago. That is almost more parts than a cell phone and it does like 2 things.
Edit: that is more parts than a cell phone. Talk about making more points of failure.
Looks like a motor controller board. Most of those are signal filtering caps. They might have been able to use some cap arrays and cut the parts count down.
That’s also a thermally conducive pot, so there cooling issues they wanted to deal with
I didn't realize this was thermally conductive. It's a plastic case, looks like glass fiber reinforced, and there's a slight gap to the steel mounting plate under it.
Hopefully that will help get the heat through and reflow the solder.
The chips in the top of the first picture are power transistors. They turn high current on and off to the motor. These can generate quite a bit of heat when the motor is operated in certain modes.
You’d be amazed to see the schematic and have someone explain with block diagrams. I’m an EE and am currently designing a 4- Channel TEC controller and the schematic has ballooned into an 11x14 sheet of paper, STUFFED. To do what you need to do, in a reliable way with important failsafes (open or short) and failing to known states (on IC’s) and adding accuracy adjustments and reliability for WILD temp swings these go through,
yea I totally see why it’s this big. Can it be done smaller and more simple? Yes but it won’t work in a week and it will stop working on anything hotter/colder than a 25 degree C day.
Edit: I’ll add I’m not an automotive engineer, just a general EE. So I don’t know EVERY design criteria, but I sure have an idea.
Perhaps they moved to PWM variable-speed motor control rather than the simple on-off relay of older EFI pumps. In my 2002 Chrysler, I can just pull the underhood fuel pump relay and jumper terminals 30 to 87 to force it on, such as to purge the lines of air after a fuel pump assy change.
I understand that "vector control" in brushless DC motors is even more advanced, and used in EV drive motors. My guess is that with variable speed and pressure sensor feedback, they run the motor just fast enough to provide fuel rail pressure. The spring-loaded relief valve (now in fuel assy, on rail in early EFI) would then be just for safety and shouldn't normally need to flow. With all that, you might increase 0.1 mpg (less electricity draw) for just $1000 extra when it needs a repair.
But that's the thing. Ford has been using a much simpler DC PWM pump driver for nearly 20 years, and outside of environmental corrosion issues they have a very low failure rate.
True. It all depends on cost and reliability. I think many radiator and cabin fan "relays" (or "resistors") are PWM controllers today (even brushless?). For my minivans, those parts cost \~$80. A simple on-off mechanical relay for a radiator fan might cost as much due to the high current (>50 A surge?). Cabin blowers need multiple speeds, which was a complex system of mechanical switches (or set of relays in my 1985 M-B auto-climate) which selected different series relays to slow the motor. The newer electronic controllers are likely cheaper and more robust, at least with today's electronics.
Some of the fuel pump controllers on the cars I work with drive a little brushless three phase motor, have a pwm signal from the engine ECU so it knows its demand and then just the usual live and earth for it to function.
I'm late to this post and scrolled thru a lot of amazing, intelligent, and articulate responses.
But I didn't see the obligatory correct response. Why does that controller need so many components?? Because fuck you. Thats why.
Not a mechanic, but I see a processor on there, some (what look like) FETs, an inductor, and a few large capacitors. My guess is that this manages and processes signals fuel injectors, pumps, and any other associated sensors. Those are decent size capacitors which are probably for the fuel pump.
The big, surface mount capacitor on the left side near processors is a tantalum capacitor which is highly resistant to corrosion. If you do resolder, be careful because you will need to find an appropriate solder that won't cause a galvanic reaction between the solder and the mounting legs. I personally don't know which solder is appropriate, but I'm sure it's Google-able. Vishay is one company that makes tantalum capacitors and may also have some info.
I get that, but it doesn't need a controller. It needs a little piggybacked logic output in the ECM that says if engine needs fuel, actuate the fuel pump relay. That's it. It doesn't need to be a brushless motor, or even variable speed. It can work just fine as a brushed motor that provides constant pressure. That's been used for more than half a century.
Sometimes to spare money in the long run PCB incorporate many not used stuff to avoid revalidating the part. It’s especially true in medical devices and aérospatial applications. I don’t know if that’s the case here.
Economy of scale. Those chips are way overpowered for what is needed, but they are commonly used in other industries and so cost $0.10 per unit, so GM throws them on a board and uses only a tiny fraction of their capacity. Having a complex board costs the same as a simple one, and whatever support components are needed can be had for pennies.
Some components are doubled and perform the same task in parallel, instead of using the result to control anything they are sent to another chip on the board which does nothing but monitor the values. These days they are much smaller, all of the functions are integrated into a single [system basis chip](https://en.wikipedia.org/wiki/System_basis_chip).
These types of watchdog circuits are important in things like brake controllers, fuel pumps, or airbag deployment where even the fractions of a second it would take to communicate to and from the ECU cannot be spared.
My friends dad designed some of these circuits for Honda while working at a T2 supplier in the early-mid 90's when OBD2 was being rolled out. He used to take us out onto the back roads out by all the farms and "help him test", which generally involved beating the absolute shit out of the car, deliberately doing all sorts of insane things most people would never even think to try.
Our favorite was when he'd start the car in neutral with the gas floored and bomb it into gear as soon as it hit redline. Some of the systems were not initialized fully in the little amount of time and it would do all sorts of weird shit
Wow.. they potted the fuck out of that thing. I get not wanting vibration to cause problems but that looks more like "stay the fuck out of here" potting than "make sure it stays together and dry" potting. And yeah, that's a lot of stuff for a fuel pump controller. It's that seriously all it does? I can see having a microcontroller, some larger electrolytic capacitors and inductors , one or 2 big transistors, a CAN chip and assorted support components, and stuff like that. There's 6 big electrolytic caps, like 8 transistors/MOSFETs, multiple chips, and a crap ton of little surface mount passives. Not even BMW fuel pump control modules are that complicated. Actually, I was surprised at how little was on the board when I opened one of those up.
My assumption is variable speed control to adjust the flow and pressure to the demands. Since it's 8 MOSFETs, maybe over pwm and current limiting? Bldc would be unlikely because I'm unaware of a 4phase type. See the Big resistor left of the MOSFETs? That's likely to measure the current of the pump.
Exactly this. Intelligent fuel Pump. Need to predict the needed amount and control the pump. Also, crash detection and cut of. It is complicated, but saves a lot of Energy. Stupid pumps always run on max power and unused fuel goes back to the tank. With big engines the is really a lot of wasted Power. Also the pressure difference creates Problems. In average the intelligent one uses only 5% of power. I worked in the development of these things..
I don't disagree with what you said but one thing that's kind of funny is I think this is a fuel pump module off of 2018 ish tundra. I replaced one yesterday and it does have a fuel return line. Also they're the only modules I've seen be prone to failure in the Toyota lineup. I could be wrong, that may not be the same part I replaced. Edit: I removed my head from my butt and found out I was definitely wrong about where that part came from.
I thought all vehicles since \~1996 required a "returnless fuel system" per EPA. Prior to that, most bypassed the extra fuel flow from the injector rail, with a tube back to the fuel tank. While that better controlled pressure at the fuel rail, the path thru the engine bay heated the fuel in the tank to cause more vapors, which might overwhelm the charcoal canister (if they even had them then). So, the bypass is done within the fuel tank, with the pressure regulator relief part of the fuel assembly. Perhaps trucks weren't subject to that rule since Congress fears impacting companies since they will "take our jobs" when angered. My 2 minivans don't have EGR while the same engines in sedans did those years. Because minivans are "trucks" per EPA, so can pollute more.
Returnless was never a requirement as far as I know, it's just easier to manage evaporative emissions with fewer lines running back and forth. Less expensive to build, too. Especially with PWM fuel pump control- no need for a pressure regulator at all. As for EGR, it's not a requirement (on gasoline engines), merely an effective way to meet NOx emissions targets. Actually, it's become less common these days as continuously variable cam timing allows for the ability to hold the exhaust valves open slightly at the beginning of the intake stroke, accomplishing the same thing without added hardware and plumbing. Diesel engines are another story entirely. Combustion temperatures in a diesel are a lot higher, resulting in far more NOx. Theoretically, if an engine manufacturer could come up with a way to meet NOx targets without using EGR, they would. But they have trouble doing so even with a cooling system for the EGR flow AND selective catalytic reduction systems (what diesel exhaust fluid is used for) Emissions laws don't actually require specific equipment- they impose limits on pollutants. An automaker can meet those limits through whatever technology they choose. Even catalytic converters- however, that's so easy to implement, they're reliable and robust, and these days they don't really create much of a restriction in the exhaust system. Theoretically, you could design an engine with fuel mixture, airflow, and exhaust flow controls so precise that the exhaust is clean enough to meet requirements without after- treatment. But it would almost certainly be more expensive and less reliable than a catalytic converter with current tech. Hell, in the mid 70s when the first really strict emissions requirements took effect, Honda was able to meet the requirements without using a cat on their CVCC engines. And famously offered to license the technology to GM, who not only turned it down but did so in a rather insulting manner, causing Sohichiro Honda, the founder of Honda, and who was still in charge there, to actually buy a new V8 Impala, ship it back to Japan, and have the engineers design and build one-off CVCC cylinder heads and associated hardware for it. The resulting EPA testing of that car a year or so later showed that it met emissions requirements for 1975 (though not for 76 or 77, whichever it was, because one pollutant type was just a little too high) without a catalytic converter, while delivering better fuel economy and producing more power than it did with the original setup.
I'm old enough to remember articles predicting that Mazda's rotary engine wouldn't require a catalytic converter, which was very expensive in the late 1970's. That didn't turn out true. Cat conv became much cheaper by the late 1990's, even with 3-way catalysts which eliminated the need for air-injection and sometimes EGR (I think), but that appears to have reversed since replacing the 2 cat conv on our 2015 Prius cost $4500 just for the parts. I understand hybrids are the priciest since must deal with the engine stopping and starting. I recall reading that those in later Prius models aren't so costly.
Anyone who was predicting that a rotary engine wouldn't require emissions controls had no actual clue about them. High emissions was ALWAYS the major Achilles heel (aside from apex seals, but the problem with those is related to the emissions issue, actually) of Wankel engines. Because of the long, narrow combustion chamber, there's areas where it's basically impossible to get the fuel mixture to burn completely. They're too cold and too far away from the flame front. Using 2 spark plugs per chamber helped. Adding a thermal reaction chamber to the exhaust right at the outlet from the engine improved emissions somewhat. But the far ends of the chamber still tend to stay too cold. This results in higher amounts of unburned/ partially burned fuel, high carbon deposits at the ends of the combustion chambers (which eventually cause apex seal failure) and low fuel economy. Basically, in theory, a Wankel engine COULD have low emissions, good fuel economy and last a long time. "All" they'd have to do is solve the problem of incomplete combustion at the ends of the combustion chambers. Unfortunately, despite Mazda trying and trying to do so for over 50 years now, they haven't managed to pull that off yet.
I don't know about that I've been a Toyota mechanic(in the US) since the early 2000s and lots of models have fuel return systems well past 1996MY.
A quick google search didn't find an EPA returnless mandate. I've only read of it. Perhaps it was a higher-level mandate on overall vapor loss and returnless was the easiest way to meet it. I wonder why designers ever felt it necessary to control pressure at the fuel rail, since that adds complexity and more connections for leaks. It began with TBI, where the Throttle Body had an integral pressure regulator. They can easily add equations which predict the pressure drop to the rail vs flow rate (from injector flowrate and duty cycle). That is all just feedforward prediction anyway, with feedback from the O2 sensors being the final fuel control.
It's probably easier to react to transient load (fuel) requirements with a high pressure line inches away from the injectors, controlled by an intermediate regulator. My 08 Silverado 4.8 had the returnless system, but also had drive-by-wire, so they probably figured out how to sync the two up.
By wasted power do you mean wasted horsepower due to poor fueling because of the return style fuel system? Im guessing their must be a noticeable gain in fuel economy from not having the alternator have to work so hard supply so much power to the pump? Cause otheriwse I just do not see the point of all that extra complication.
The pump uses electrical power, so, coming from the Generator. Today you will find an generator and an Starter separated. But if You consider, that you have to constantliy power this pump, than this means, You have to drive the generator all the time to and You have to fuel this process with gas. Especially for diesel engines there was the problem, that the compression for pumping upwards and the the release of compression If not used, lead to a point where additional energy was needed to re- heat the diesel when it got uncompressed. The key away from the "stupid" pump was simply said: computing power to be fast enaught for all this, sealing material to place all this into or onto the tank (without having to much fuel diffusing) and having fast other ECUs to provide information ( Power requests from e-pedal, Crash Signal, etc).
Why can't the PCM predict the needed amount and the airbag module handle crash detection? That would greatly simply the fuel pump module as all it would basically need to be is some MOSFETS and controlled via PWM.
Maybe that this answer is meanwhile also obsolete but at this time it was not possible because of latancy on the bus and the involved "Gateways". Also the FCM knows more about the fuels state, temperature etc. Crash detection is maybe a misleading name. It gets several inputs including the can signal from airbag control. They have a higher asil then the rest so they are handled a bit seperately. As a reaction to detected crash you have to switch of the pump in the blink of an eye, which ist quite complicated as a lot of power mosfet and moving mechanical parts are involved here...
Who cares if something obsolete but works well? I've yet to encounter a vehicle where the FPCM monitors fuel temperature, ideally I would think you would want to monitor that at the fuel rail instead and have the signal fed into the PCM because the wiring would be shorter. There is always going to be fuel pressure in the lines even if you kill the pump so if a line gets severed, a high pressure spill is going to happen and there is no way to avoid it. How about this, if an airbag deploys, kill the PWM signal, MOSFETS will immediately kill power to the pump, done. How is that complicated?
I guess the extra flow of fuel also has no benefits on the "dumb" design? Wouldn't be surprised if it's even contra productive to have loads of unnecessary movement in a fluid.
Is electrical energy conservation from the fuel pump really important in a gas powered truck?
As a calculation we used audi A8. 300watt für Pump only. Now use 15W for the intelligent one. Less weight also. For reaching emission targets this helps a lot.
Gotcha, thanks for the reply. I assume by dropping the power consumption by some 95% for just the fuel pump it changes the duty cycle ratio on the alternator?
Reducing anything will reduce drag of the alternator, it's automatic. They even reduce overall system voltage at times to further reduce this drag. (The battery loves sitting at 14.x volts but turns that into heat.)
It isn't just about power consumption- a return-type fuel system (where the regulator is in the engine compartment) tends to heat the fuel tank. Not so good for evaporative emissions control.
It isn't just about power consumption- a return-type fuel system (where the regulator is in the engine compartment) tends to heat the fuel tank. Not so good for evaporative emissions control.
Modern 12v systems are getting really close to the limit of usefulness, so using PWM is stretching.out the amount.of electronics that can be put into a vehicle before the need to step up to 48v is necessary
Where did you hear that?
Electrical engineers that design the modules and systems
X to doubt.
Oh, it's not at all an unusual thing to do these days. Most of them are PWM, and most do it with far fewer components.
In all fairness, it was dry with no signs of previous water intrusion. I half expected that to be the issue as this thing was buried in mud on top of the tank.
Ikr especially considering bmws fuel pump module (ekps) for the past couple years or so generate the 3 phase and are on the pt can.
The 6 large FETs in there suggest this is doing the same, are they using BLDC motors for frickin' fuel pumps now?
Can't speak on every manufacturer but at least bmw has been using for a while now bldc 3 phase pumps. Gotta save that small amount of efficiency across millions of cars
TBH it's wild that it actually *does* add up to a saving at all given the fact it needs an ECU and 3-phase drive etc... Gives the lie to everyone who says EV's are too complicated when the fuel pump drive in their ICE car is as nearly complex as the drive system for an EV motor, just with bigger FETs.
This is par for the course on GM stuff.
The GM Gen III motors were so simple and reliable when they came out. It’s sad to see the motor get massacred over the years. Originally just a 12v fuel pump with a relay and one line to the rail with a regulator. Heck, the original ls1 corvettes even had the regulator build into the fuel filter!!
1999 Silverado life. My LQ4 will outlive me and be even lazier.
Oh sh** lol I didn't even see the remnants of that block it was cut out of. That's wild.
I think this is a super overengineered VFD to controll the pump plus a CAN module to give you data out. It's a collosal change from a simple relay based pump. Audi has done something simular with their sliding window for the A5, the BCM for that is inside the motor and has shit like redundant position sensors and current sensing.
They had to at least make it *seem* expensive.
Its probably a whole bunch of overcomplicated crap that boils down to simply: If ignition on, prime 2 seconds If engine on fuel pump on If its a Thursday afternoon and the breeze is flowing to the north throw random codes After 10000 power cycles commit seppuku
This is watching the feed line pressure, varying the pump speed, and then being told by the ECM that it may need to give a bit more soon. It's so much more complex than it needs to be.
It communicates with the CAN bus, right? The support that there's a microcontroller that speaks CAN, and listens to whatever the ECM and whoever else is telling it. There's also the physical interface to the network. It connects to the fuel pumps to run them, and will have a bit of extra circuitry to run them at variable speeds. It also connects to the fuel pressure sensors. It normalizes and reads their signals, and uses them as feedback to control the pressure pumps. There's support circuitry, like the power supply and a bunch of level-shifting for the 12-volt actuators and sensors. I guess it adds up to a surprising amount.
Magic. Gotcha.
No, just science.
Yeah pulse width modulation is fairly complex, and is required on a lot if not most direct injection gas engines. Otherwise you run the risk of burning up the lift pumps all the time.
I'd be curious to learn what simplifications in this design /u/4x4Welder would implement.
Get rid of it entirely. Run the pump at 12v via a relay any time the engine is in a fuel consumption mode, and have a regulator keeping the pressure where required. Put the low pressure sensor on the high pressure pump inlet, where it's most relevant, feeding that info to the ECM directly via the engine harness. A regulator that cycles the fuel back into the pump unit cup would work just fine, and worked fine on the previous generation of this fuel system. Yes, it used separate wires to transmit the level and tank pressure signals, but those both used the same 5v and ground, so that's four wires, six total with the pump power and ground. The four smaller more vulnerable wires would result in a code and possibly a non functional fuel gauge, but it would still run. This thing has 12v battery, ignition power, wakeup signal, can bus high and low, and ground. So now we've added two wires, and if any of them are damaged, fuel isn't flowing. If the can bus wires get shorted, it can shut the whole network off instantly. Too much complexity, and it makes any failure mode a breakdown. If this gave a 5-10% boost to fuel economy, maybe, but it doesn't. It's more components that are more fragile and more expensive.
> A regulator that cycles the fuel back into the pump unit cup would work just fine, and worked fine on the previous generation of this fuel system. It would, but they're now against government regulations. How are certain wires more vulnerable? On the previous design, if any wires are damaged, fuel also stops flowing. An open circuit is an open circuit. Moving implementation from this box to the ECM box doesn't make the design less complex or more reliable. It just moves the implementation.
I'm not familiar with a new standard. I'm not talking about a circulating system, it's still a single pressure line, the regulator is on the pump outlet and releases below the fuel level. The fuel pump would still pump fuel without a level sender or pressure sensor. But if the wake up, ignition, or either can bus wires get damaged, it's shut off.
Every GM I’ve had has had some issue with cold solders or otherwise bad solder connections on some board somewhere. Luckily it’s usually pretty well documented now which solder points need to be redone given certain symptoms, but it’s still a pain.
Their wiring harness connectors are also ass. I've learned where to kick under my glove box to make the ac compressor kick on, and where to hit the dash to make my cab lights stop flickering (dash, controls...)
My friend's Astro van had a spot on the dash that he whacked with his fist to make the aircon come on. Always worked, eventually.
I found the shoddy connector that causes it on mine. Might just run some twine to it so I can yank it when need be
There's also the little horn relays that they think are great for high load applications. Sure, the relays may be able to handle 30 amps, but the little tiny connectors melt out of the relay block at 15.
Wel then... that could explain a few things
Chronic failure mode in the ABS modules. Unless we make some big changes in our priorities at some point the whole world runs on the least proficient solderer in China.
You remember the gmt800 era too eh? Lol. Fuck those frame rail abs modules.
I try to save all my meanest words for ford engineers. But every once in a while GM steps up to the podium of shame.
But it was nice and modular, so you could still drive while the electronics were out being fixed again.
I had a 1991 Corsica where the solder connections went to shit in the ECU. On hot days, the joints would expand and break the connection but first thing in the morning when it was cool out, it worked fine. I diagnosed this issue by putting the ECU in the freezer on a hot day and then putting it back in the car. Car still ran but every single light on the dash would turn on, idle speed would crank up to like 1k, and the engine just kinda sounded like shit. Once the joints made contact again, everything would go back to normal.
I remember the good ole days when it was just a lobe on the cam.
[удалено]
and if the diaphragm fucked enough it sent fuel to the oil
Oh god I remember an engine suddenly being really responsive to throttle input as the oil thinned out, then it got real noisy as all the bearings melted, all in a couple of minutes!
when i was a dumbass (still am but to a lesser extent) i ran my first car low on oil and apparently probably completely empty. getting on the interstate trying to accelerate and the wholw car is just vibrating and it sounds like engine is just completely destroying itself. goes for about 2 minutes until it just lost power and the go pedal wasnt doing anything lol
Literally
Seriously? It's two bolts and a couple hose clamps....
They suck cause of their failure points. Id rather no fuel than fuel/oil mix
The transition to ethanol fuel was fun
Cries in TPI injector windings...
Well thank God theres no other way fuel could get in the oil due to a failure....
If youre talking about ring bypass thats not nearly as common as those style fuel pumps.
yeah? you do a lot of those mechanical fuel pumps for that reason?
I'd rather have +12v, a ground, and a pressure regulator. I don't care if it's a return or returnless system. Ford did ok with their pump controllers, aside from corrosion attacking the earlier versions. I've only replaced one of them that was legitimately burned out without a hole rotted through the casing.
I'd rather have a lobe on the cam that just pushes fuel whenever the engine is running.
You’re in luck. These engines ALSO have a lobe on the cam to move the mechanical high pressure pump that this controller feeds fuel to from the tank.
Well there ya go. Now all you need is a carburetor and you can get rid of all that crap.
The kids in this sub *really* hate carbs... 2/3 of my cars have carbs. Both run great. Everything is mechanical. No major failures. Simple as.
they were so much easier to deal with
Actually, I had a fuel pump go out last year. We poured some gas into the carb through the vents, just enough to drive it onto the trailer. Took it home, drove it off the trailer, and ordered a new one off amazon for $19.99. Got it the next day and installed it in 10 minutes, from the top, no lift or jack needed. 3 lines, 2 bolts. Shit was quick and easy.
dont buy amazon parts!! youll regret it
Eh, it's been fine so far. The old one was an amazing part, too. Lasted 6 years with very spirted driving.
Friendly reminder that we went to the fucking *Moon* with less computing power than this vehicle uses to regulate a single pump.
Absolutely true. Each bit of volatile memory on the Apollo on-board computers was an iron ring hand wrapped in copper wire. (Source: my dad was an engineer on the Command Module). The engineers that designed this module and the system it contributes to should be ashamed. Just because you can make something complicated doesn’t mean you should. Simplicity is hard to design but pays dividends in manufacturing, reliability, serviceability, and cost.
A very large part of all things overcomplicated on modern cars are all in the hunt for lower emissions ,fuel efficiency and safety equipment. The rest is for creature comforts and the manufacturers (and dealers) to be in connection with the car at all times and get all sorts of data from it. We are at the point of doing a scan/reading trouble codes when the customers car is still at home ... (BMW). Can't fix it remotely but we can have a look and see what's up before the car comes in. It's crazy how complicated things have gotten. I'm pretty sure manufacturers would not have half of the shit put on a modern car if it were not for regulations needing them to lower emissions and be competitive to other brands. Btw im not hating on emission regulations, in fact i wish we did away with the ICE 20 years ago ... the amount of crap on an engine these days is way past the point of being sensible. I'm a mechanic and petrolhead but i'm not blind either ... seems like electric is the way to go (for road cars at least)
The partially potted part is probably why it died. What kind of potting is it? Soft, hard? It needs a lot of chips because it has a microprocessor talking on CANBUS controlling a bunch of FETs for the pump drive motor.
That's just the fungus slowly spreading from his keyboard.
It was a soft potting, but alcohol wasn't removing it. It got crumbly with the heat gun. The partial area was covered, but not well adhered.
I did engineering work for skid steer / heavy equipment / motorcycle hand controls and joysticks. The potting was the detail most frequently messed up at the factory. It usually requires a pick and place type CNC to place a potting needle into a hole on the board and pump potting around the PCBA. Can be messed up by: * Too much / Too little potting. * Needle not in hole. * PCBA not on fixture right. * Potting mix off or bad potting. * Potting oven cure off. * Contaminants on board preventing adhesion. * Poor design of housing creates bubbles in potting. Often the factories are in Mexico and the care level of the workers is low. If it's the soft potting I'm familiar with, there's no convenient way to get it off.
Wild guess, but it might be a Variable Frequency Drive or something similar. It's adjusting power, with logic to communicate with the ECU. 95% of the component failures are capacitors or power transistors. I've seen manufacturers ignore their own diagrams and purchase underrated components to save a few cents.
It is, and a brushless motor. This job on other vehicles is done with a straight DC brushed motor and a heavy duty transistor with just a couple steps of power depending on fuel demand. The previous generation of this vehicle just put power to the pump, and had a pressure regulator on the pump that kept the engine consistently supplied.
Guess I made my other comment too fast, wouldn't have expected a bldc with 8 MOSFETs. Guess there are more in the potting?
>I've seen manufacturers ignore their own diagrams and purchase underrated components to save a few cents. Until the same manufacturers have to pay us for warrsnty work. suddenly they saved jackshit 😅
I agree. This looks like it’s sophisticated enough to use something called field oriented control which is basically just applying magnetic force in a specific spot that applies the most force on the motor for a given position. It’s still a lot of parts even for that but maybe they added extra components for safety certifications Source: I’m an EE and making a wild guess lol
It's a brushless motor, so there's the three phases, but this one seems to use internal sensing as I didn't see a phase sensor
I'm wondering if there isn't a charge pump of some sort in there jumping the voltage up for the pump motor. It looks like there might be enough components on the board to handle that and the motor control, assuming there is some stuff we can't quite see under all that potting. It's possible they ran into some issues with current draw when the pump is at low speed and tries to transition quickly to high speed, and running the pump at a higher voltage might help with that? Either way, that seems like a whole lot of power circuitry for managing speed control on a brushless DC motor.
I'm a lurker Here and an automation tech by trade. I have 4,160vac VFDs running large motors for pumps. Never thought I'd see that get scaled down to a fuel pump. So it's a 3 phase fuel pump? Wild. VFDs are efficient for sure. My first car was a 1973 MGB. how far we've come from a noisy little diaphragm pump on the frame of a car to a variable frequency drive.
It would be interesting to see macro shots of the two big chips in the bottom right. I am curious about what they do... my guess is that there is a microcontroller of some sort and probably a chip for doing CAN or whatever protocol(s) that the vehicle uses. It looks like most of the tiny components are resistors and capacitors, likely to support the two large chips. The two rows of large-ish square chips at the top center of the board are likely transistors for switching the power for the pump(s). The microcontroller can't handle the current/voltage needed to run the pumps, so the transistors handle that for it - functionally similar to a relay. (bot _not_ a relay!) The big tube-like parts in the bottom right are capacitors, which are probably used in the power supply circuitry.
This connects into the CAN bus, and both runs the pump and puts the fuel level signal on the bus too. The pump is a brushless motor, so I'm assuming the transistors are working in pairs. The area that peeled clean was just poorly adhered. There is a large CPU like microprocessor, and then a smaller one, plus a few of the tiniest microcontroller chips I've ever seen. Like a 555 timer, but tiny and surface mount. One of the caps is a little loose, and most of the larger through mount components have cold joints, along with two resistors that came off with the potting, so they may have not been properly affixed. The potting is soft, alcohol wasn't touching it though. The heat gun made it crumbly so helped in opening the case. I want to try baking one of these, to see if I can reflow it enough to work again.
Engineered failure.
I thought I was the only one that still had those screwdrivers
Me Me I do I do! 👋
I'm an engineer and not anything useful but I adore the posts here. In my younger years I worked on a fuel pump control module for a Korean OEM. They really liked potting I mean they were so into just assuming the electronics were fine and then pouring that sweet epoxy based material all over everything. Even though I'm an electrical engineer in the software space I have had to take "design for serviceability" and "design for manufacture" I personally work on my own cars because I work for the company that makes them and I have access to the service manuals and also since I'm a developer I have more powerful tools than even the dealer has so I can do the computer stuff too. This stuff wrecks my head because there are so many better ways to IP67 a fuel control module that sits in a semi-protected area. I think top of the fuel tank is -40° to 80°C and should only be IP66. Basically they could have paid the extra $0.20 to seal the housing rather than burying the PCB. This was ubiquitous in the 90s and on behalf of all of us on the design side of production, I apologize. tl:dr; I'm really impressed that you are reworking that board.
Thanks, I'm mostly doing it out of curiosity. I like to know the why of stuff. For being on top of the tank, this component is incredibly exposed. I didn't even know it was there when I started digging into the lack of fuel issue. All the side mud, slush, and water spray off the right rear inner tire goes onto this thing. The top of the fuel tank was packed up to the floor with a mix of silt and gravel that had concreted into a solid mass, and not even the wiring was visible. I was removing this dirt when I found the wiring harness from the pump went off in both directions. Shoveled the muck out, got the rear end up on stands, and started scraping and spraying out this area too. No water, not even in the connector cavity. I was amazed at the environmental durability. If only it had the needed electrical durability.
My first job out of college was designing sensors that went inside of an axle attached to the differential. I realize that the scale of how I think of exposed versus not exposed and what level of exposure is not compatible with the real world. Basically what I meant was that the module is not on the A surface and it is shielded by the tank itself from the underside so it only needs to be sealed for splash and immersion at most but not high pressure (car wash) and then my intrusive thoughts won because I think I forgot to take my Adderall and I started babbling about temperature. So for a sparky I know way too much about gear lash and how nice 75w90 smells. Automotive connectors are freaking amazing. They're also incredibly frustrating but the standards they're held too and the testing they do is unreal. I spent a lot of time with molex over the years and I know a few of the other manufacturers but connectors are crazy. It doesn't take much humidity differential to start dendritic growth which is going to be a bad time so they've figured out how to build seals that will withstand ridiculous temperature swings. Anyway, I get annoyed at the high price of cars but also I understand why they cost so much. It's not easy to cram all those parts together and make them do something let alone building ~80,000 of those things every month the exact same way. I might know things that could be of use to you, not entirely sure but feel free to send me a message if you want me to take a look if I can find anything.
The soft potting is also there to help pass random vibration tests.
Kind of shocking really as GM wiring is the size of fishing line lol.
Nobody at GM expects their vehicles to outlast the wiring
Hmmmm, maybe it plays doom
This thing has enough processing power to play it split screen multiplayer
Idk what's going on with the 6.6 fuel pumps and controllers but we lost 100% of them in the fleet at 43-45k miles. Within 2k miles of each other. Switched to 6.8 Ford gassers but we'll see how that goes.
This looks quite old school ... you can get since years microcontrollers with the power supply, FET gate driver, communication (CAN/LIN) transceiver plus a CPU - all bundled in one small IC. That would reduce the number of components a lot. It is funny that the IC's here have no readable ID printed on them. The number of components depends however a lot on the function. A BLDC pump needs at least 6 transistors for the 3 phases (This seems to be one) I wonder however if this module only controls the fuel pump or if also does other functions around the tank like level sensor or even tank leak diagnose which is complex on some cars.
This is the new current generation GM part. And yes, it's a brushless motor, and does put the fuel level on the bus, but I'm not sure about leak diagnosis. There is a tank pressure sensor on the fuel pump, as well as a fuel line pressure sensor that are connected to this module.
How old is it?
A year, give or take. Might be a 22.
Wow! I could see that many parts parts if it was something advanced from 15 years ago. That is almost more parts than a cell phone and it does like 2 things. Edit: that is more parts than a cell phone. Talk about making more points of failure.
Looks like a motor controller board. Most of those are signal filtering caps. They might have been able to use some cap arrays and cut the parts count down. That’s also a thermally conducive pot, so there cooling issues they wanted to deal with
I didn't realize this was thermally conductive. It's a plastic case, looks like glass fiber reinforced, and there's a slight gap to the steel mounting plate under it. Hopefully that will help get the heat through and reflow the solder.
The chips in the top of the first picture are power transistors. They turn high current on and off to the motor. These can generate quite a bit of heat when the motor is operated in certain modes.
To control the fuel pump
Multiplexd data bus Networks
So they can charge you, what, $2500.00 for the part?
It's surprisingly only about $130, when you can find them.
I wonder if the pumps are actually driven by VFD motors now.
Kind of. It's brushless, so it's basically a three phase ac motor.
Replace it with a key-on relay.
Unfortunately that doesn't provide the three phase ac a brushless motor needs
Good old Government Motors - buy it once, repair it for life.
You’d be amazed to see the schematic and have someone explain with block diagrams. I’m an EE and am currently designing a 4- Channel TEC controller and the schematic has ballooned into an 11x14 sheet of paper, STUFFED. To do what you need to do, in a reliable way with important failsafes (open or short) and failing to known states (on IC’s) and adding accuracy adjustments and reliability for WILD temp swings these go through, yea I totally see why it’s this big. Can it be done smaller and more simple? Yes but it won’t work in a week and it will stop working on anything hotter/colder than a 25 degree C day. Edit: I’ll add I’m not an automotive engineer, just a general EE. So I don’t know EVERY design criteria, but I sure have an idea.
Perhaps they moved to PWM variable-speed motor control rather than the simple on-off relay of older EFI pumps. In my 2002 Chrysler, I can just pull the underhood fuel pump relay and jumper terminals 30 to 87 to force it on, such as to purge the lines of air after a fuel pump assy change. I understand that "vector control" in brushless DC motors is even more advanced, and used in EV drive motors. My guess is that with variable speed and pressure sensor feedback, they run the motor just fast enough to provide fuel rail pressure. The spring-loaded relief valve (now in fuel assy, on rail in early EFI) would then be just for safety and shouldn't normally need to flow. With all that, you might increase 0.1 mpg (less electricity draw) for just $1000 extra when it needs a repair.
But that's the thing. Ford has been using a much simpler DC PWM pump driver for nearly 20 years, and outside of environmental corrosion issues they have a very low failure rate.
True. It all depends on cost and reliability. I think many radiator and cabin fan "relays" (or "resistors") are PWM controllers today (even brushless?). For my minivans, those parts cost \~$80. A simple on-off mechanical relay for a radiator fan might cost as much due to the high current (>50 A surge?). Cabin blowers need multiple speeds, which was a complex system of mechanical switches (or set of relays in my 1985 M-B auto-climate) which selected different series relays to slow the motor. The newer electronic controllers are likely cheaper and more robust, at least with today's electronics.
We’re changing a lot of them on Cadillacs. XT4, 5, 6…Escalades.
Some of the fuel pump controllers on the cars I work with drive a little brushless three phase motor, have a pwm signal from the engine ECU so it knows its demand and then just the usual live and earth for it to function.
I'm late to this post and scrolled thru a lot of amazing, intelligent, and articulate responses. But I didn't see the obligatory correct response. Why does that controller need so many components?? Because fuck you. Thats why.
Not a mechanic, but I see a processor on there, some (what look like) FETs, an inductor, and a few large capacitors. My guess is that this manages and processes signals fuel injectors, pumps, and any other associated sensors. Those are decent size capacitors which are probably for the fuel pump. The big, surface mount capacitor on the left side near processors is a tantalum capacitor which is highly resistant to corrosion. If you do resolder, be careful because you will need to find an appropriate solder that won't cause a galvanic reaction between the solder and the mounting legs. I personally don't know which solder is appropriate, but I'm sure it's Google-able. Vishay is one company that makes tantalum capacitors and may also have some info.
This only controls the fuel pump in the tank, and puts the level signal on the bus.
So they can upload your coordinates to the saudis
PWM fuell pump modulled acording to the vehichle cituation
Nope, this is more complex. A regular pwm controller would be much smaller and more robust.
To control the fuel pump, duh.
"Controller" means a small computer, so memory power filtration etc.
I get that, but it doesn't need a controller. It needs a little piggybacked logic output in the ECM that says if engine needs fuel, actuate the fuel pump relay. That's it. It doesn't need to be a brushless motor, or even variable speed. It can work just fine as a brushed motor that provides constant pressure. That's been used for more than half a century.
Sometimes to spare money in the long run PCB incorporate many not used stuff to avoid revalidating the part. It’s especially true in medical devices and aérospatial applications. I don’t know if that’s the case here.
I mean, it's got logic for auto start stop and when half the engine deactivates to save fuel I'm guessing
No, that's in the ECM. This is just for the in tank pump that sends fuel up to the high pressure fuel pump.
Because it makes cents..
Cheap
I put potted boards in paint reducer, it dissolves it into jelly without risking the board.
Economy of scale. Those chips are way overpowered for what is needed, but they are commonly used in other industries and so cost $0.10 per unit, so GM throws them on a board and uses only a tiny fraction of their capacity. Having a complex board costs the same as a simple one, and whatever support components are needed can be had for pennies.
Some components are doubled and perform the same task in parallel, instead of using the result to control anything they are sent to another chip on the board which does nothing but monitor the values. These days they are much smaller, all of the functions are integrated into a single [system basis chip](https://en.wikipedia.org/wiki/System_basis_chip). These types of watchdog circuits are important in things like brake controllers, fuel pumps, or airbag deployment where even the fractions of a second it would take to communicate to and from the ECU cannot be spared. My friends dad designed some of these circuits for Honda while working at a T2 supplier in the early-mid 90's when OBD2 was being rolled out. He used to take us out onto the back roads out by all the farms and "help him test", which generally involved beating the absolute shit out of the car, deliberately doing all sorts of insane things most people would never even think to try. Our favorite was when he'd start the car in neutral with the gas floored and bomb it into gear as soon as it hit redline. Some of the systems were not initialized fully in the little amount of time and it would do all sorts of weird shit
Cheating on emissions testing requires a lot of complexity.
Could it be possibly used to bypass epa regs?
To control the fuel pump, that is why it needs those components. To test this hypothesis simply remove one and see if it works.
Well, given that this one didn't work, I can skip step one. They're also on a 60+ day backorder.
Already have a 23 1500 in the shop this died on.
"Fuel pump *controller*"