gooffeyguy
Tom
@swathdiver had an issue finding the FPDM on his a couple years back I believe. It wasn't were it was supposed to be
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Ethanol percentage flex fuel
- Thread starter wsteele
- Start date
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swathdiver
Full Access Member
That was the solid state relay for the trailer brake controller. I have no idea where the fuel pump computer is though! LOL
iamdub
Full Access Member
OK, here is another twist. I decided there was enough confusion when looking up part numbers for my FPCM, that I decided to drop my spare and get exact part number on my FPCM. Guess what, no FPCM on my truck that I can find. Whatever my truck is doing to manage fuel pressure, it seems very different than previous and later model years. I went and looked to see if maybe they carried the pressure regulator over from earlier model year, didn't see anything. Frankly, it is starting to piss me off.
I thought the FPCM is in front of the tank, mounted to the face of a cross member, kinda at a 45° angle.
I think they have moved around. There is enough evidence of that, that some of the better informed YouTube clips on the subject have a pretty long drawn out explanations of why some of the other modules in the area, ain't it.
Frankly, right now, it really seems like the FPCM team didn't have their shit together when the "cut off" date was there for spec zero for NNBS. So the overall powertrain design team went to plan B and used a hybrid approach, using the fuel pump from previous years and some code in the PCM which seems to tell the pump when to rev up. In the end, the "Virtual Ethanol" coders were likely left in the lurch with not enough actual sensor inputs to accurately deduce what the Ethanol percentage was, so like the good troopers big company coders are, they faked it, at least and until they had some more hard data their algo's could rely on to be more robust. Seems by 2008, they were just a little shy still.
But then, I find the 2015 and on, FF engines have a Flex Fuel Sensor, so it seems, as miserly as GM is about putting hardware back in, maybe they just realized the team lobbying for "we can do it in code" maybe were smoking a little too much of the Ganga.
Sorry to be so cynical.
gooffeyguy
Tom
In all the videos I have seen, they have them back behind the rear axle, very near the spare lift crane. But I will skoot under tomorrow and look. In any case, if it is there, it aint actually a FPCM, at least, as later models see them.
Great place for it, just across from the BM, unfortunately, like all my other explorations, just another dry hole.
I think there likely is a hint in that they used the 2006 fuel pump in the 2007. I think the pre-2007 models used a different fuel pressure management strategy as it pertains to the pump. I need to read more about the NBS gen to see if I can figure out what that system looked like.
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iamdub
Full Access Member
I thought in the back was on the trucks and the SUVs had them in front of the tank. I know when I had my tank down recently, I saw a computer-looking thing that had "FSCM" (or was it "FPCM"?) whit lots of other numbers on a white label.
I think it could well be there, at least for a few model years. I know for a fact (thanks to Ken), that the 2008 models have them, so if you saw your's there, almost for sure it was there. Mine, I am convinced doesn't have one. At least, tonight, that is what I believe.
iamdub
Full Access Member
I think it could well be there, at least for a few model years. I know for a fact (thanks to Ken), that the 2008 models have them, so if you saw your's there, almost for sure it was there. Mine, I am convinced doesn't have one. At least, tonight, that is what I believe.
Gotta love them first year problems.
