2010 6.0l e38 ecm wont turn fuel pump on

[Sharkey]

im finishing up a swap right now and having is fuel pump issues. the engine is a 2010 6.0l with a 4l60e, e38/t42 combo. the problem im having is the fuel pump wont turn on, it wont prime, and in the scanner under the bi-directional controls under the fuel tab the uel pump on and of tabs are greyed out, same with fuel pump-hi tabs. secondary fuel pump can be selected and i can adjust fuel pump pwm, however nothing happens. im running a ixed pump of a relay, triggered by pin 50. any ideas? ive done the vats patches and disabled starter checkes. an ive attached the tune file.

kevins 53 chevy 6.0l mod.hpt

[tek1229]

I'm just a newbie but with the reading up on using the egr or a/c pressure sensor with a wideband as I understand it you need to turn on DTC's for the codes corresponding to the circuits involved.. I haven't tried it yet though myself.. Could try changing them to ses enabled and no light reported..

Just an idea..

[Sharkey]

I initially had a p0230 code (fuel pump relay circuit) right from the start, I removed the code without really thinking about it. Even then I had no fuel pump, so I don't think it's the problem, but I can give it a try

[Nate007]

Yes, its J1/X1 pin 50, and add you said, you're running it off of a relay, which is all fine, but what are you running for a pump, regulator, what vehicle is it in, where are you pulling your relay power from, etc..
First thing..
Under Fuel>General>FPCM Fitted, check "NO"
Then under desired pressure, set all the boxes to 54 (That's what mine actually measured for psi w/ Walbro 392 & Vette FFR, yours may be different, but for now that's safe) except the high flow, which I entered 48.
Then under Pump Duty Cycle> set everything to 100%. This should keep your relay engaged and from fluttering.
The rest of the settings in the fuel category are stock in, but there's some I have yet to really understand, and I'm not 100% sure if they affect anything for a swap or not, but with those settings everything should work.

For your relay though, be sure pin 50 is triggering the ground of your relay, and not the positive. Verify with a volt meter, but I'm 99% sure.. I'm posting from memory and don't have reference materials handy.
Then if that doesn't work I would put temp power (hand held jumper) to the pump and verify that it works. 1-2 seconds is enough.
I'm in the final tuning stages of a 6.0/6L80 swap in a 71 Chevy 4x4, so I've beat my head against the wall more times than I can count.. After 200 miles of road testing, logging and tuning I'm still finding issues.. Message me if you have questions, im no e38 expert, but have had to figure out a ton of stuff on my own..

[Sharkey]

its a 53 chevy pickup, power for the fuel pump relay (and main power relay) are pulled from the back of the alternator. i can jump the fuel pump relay and it powers the pump. when hooking negative probe from my meter to pin 50 i see roughly 0.5v key off, key on i get 0.2 volts during what should be priming, then get 0.00v after that. i activated the p0230 code again, no change. also made the changes listed above and no different.

[Nate007]

Ok, I've got my program out this time, so hopefully we can get you going.
Have you checked changed the box under fuel pressure to indicate "Fixed"?
Sounds like the voltage you're reading is actually showing so low because it's different hz. Setting that box to fixed will send a 128hz signal to the relay.
So..
FPCM FITTED = No
Don't need to mess with the hi/low flow boxes below that.
My pressure settings in the following boxes are:
Normal = 53
High flow =48
Low flow = 58
Cold engine =58
Default =58
Fail =58

Cranking I have 55's across the whole table

Other than seeing the pump duty cycles to all 100's ice left the rest of the settings alone.

One thing to think about too.. I've lived nearly 250 miles of various conditions in the last several days, and with a stand alone pump, I've found they definitely don't like the heat! If you have a Walbro, Bosch or equivalent, make sure it's got heat shields or fresh air or whatever you can do to keep it cool. Mine got hot the other day and would barely idle. Say on the side of the road for several minutes then could go another mile, then the same for nearly 10 miles. Installed a couple heat shields and it doesn't seem to be doing that anymore. When it got hot the pressure would drop to 20psi or lower.
This is the last frame mounted pump I'm going to do. Period.
Let me know if you figure the pump issue out. Good luck.

[Sharkey]

yea its set on fixed. all my settings are very close to what you have there. funny thing about this is the vehicle it this was all in (2010 express van) did not have a fpcm, it was set for a fixed puel pump.

the fuel pump im using is a performance world 190lph, and im using a c5 corvette fuel filter/regulator. used them on a few ls swaps now, they work well for stock-ish engines. i myself prefer in tank pumps because of reduced noise and better cooling, however its not always easy convincing a customer that we need to spend a bunch of time removing and modifying the fuel tank when an on frame pump will work just fine.

ill give it another shot in the morning. if it doesnt work ill try hooking it to the secondary pump output (iirc its pin 51, but ill have to check my diagrams) and see what happens.

[Sharkey]

still no change, its still not working. i tried the secondary fuel pump output and it didnt work either

[Nate007]

I hear you on the in-tank vs frame rail deal. I finally convinced our most recent customer that something needs to be done with his '71 Chevy and it's Walbro pump.. The oem tank is behind the seat so he opted to not mess with it when we started this project, but we knew it was a wild card issue to focus on once its running. Last friday the truck kept going super lean while cruising and gradually kept slowing to a complete stop. He thought he had bad gas at first, but after meeting him on the side of the road with a fuel pressure gauge and a bug sprayer full of cold water, he realized that the heat soak had dropped his fuel pressure to the mid-20's. We carefully and lightly sprayed the few feet of exposed fuel lines under the cab and the pump/filter on the frame rail for a few minutes. The truck fired up and ran normal with only slightly lower pressure (50+/-) but wasn't stranded..
We're now ordering a new tank to modify with baffles and an in-tank pump.

As far as your issue, if your settings are the same and it's still not working, I hate to say that I'd start over with the relay wiring, because it should be working. As long as you've got keyed 12v power to the relay (in crank too) and a good relay ground, I can't see why it's not running for you..

To maybe eliminate or isolate the ecu from the equation, you could disconnect the pin#50 trigger wire from the fuel pump relay and temporarilly just put keyed power in it's place. That would tell you if your relay and fuel pump wiring is good, and from there you can check your harness and pins if the keyed powered method makes the pump work. Chances are, it's something simple. Ground issues are killer..

[Sharkey]

ive already removed pin 50 and grounded it and the fuel pump turns on. relay and all works fine. i am correct that the ecm supplies ground to the relay coil to trigger it, am i not? cant say ive seen a gm computer that triggers positive or a fuel pump relay.

one other thing, here is a print screen of my scanner when im connectedscanner print screen.png see how the fuel pump toggles are greyed out? whats the deal with that?

[Sharkey]

well nevermind. feel like a total dumbass. the wiring diagram i have isnt clear on fuel pump output, and i had it wired assuming the ecm supplies ground. i cant say i recall seeing a gm ecm outputting 12v+ for the fuel pump relay.

[Nate007]

Hey, don't feel like a dumbasss, there really isn't much of anything that's clear about swapping motors, let alone e38's. The fuel pump just happens to be one of the things I've been through and had to figure the same things out.
The fuel pump is a 12v signal, but it controls the pump via pulse width modulation (the way I understand that is that it flashes the voltage at varying speeds - or hz) but it is the + voltage that ultimately operates the pump.

Glad yo ugot it fixed though!
The fan's are another story, and there's another thread here with a write-up on that, but for a swap situation? Do yourself a favor and just put a bung with a sensor in the radiator to control the fans and don't bother with the ecu.. What a PIA..

[tek1229]

So it was just the relay being wired wrong? Sweet, an easy fix...

I'm a dealer tech for over 25 yrs and I was also assuming the ecm grounded the relay, Just took a peek on SI to see that the express van wiring shows B+ from the ECM energizing the relay.. Doh!!!

[will15]

My ls1 power switches the fuel pump relay.

[Sharkey]

yea its fixed, got it briefly fired. have to finish welding the upper rad pipe and air intake before i can run it long.

i have the fan wired up, i can toggle it on and off. i set the table to turn the low speed fan to 100% at 205. ill see if it works.

[Nate007]

I have mine set via the e38 fan settings thread, and they come a few seconds after the engine is running, and IF the engine reaches 192 one will stay on for about 90 seconds after shut down, and if it's at 196 or over, they both with run afterwards. Seems to work good that way. I'll post what I set mine too if you need it.