It's a really weird log, I don't have anything to offer sorry. Engine RPM doesn't show up at all. Some of the other data never populates either. It seems the other data starts/stops multiple times in the log-- I can't tell what is going on at all. Was he cycling the key on/off or something?
No, that?s the issue. The car dies, the key stays in the on position, so he cranks the engine over again, but then the car starts and dies. It does not idle for more than just a couple of seconds.Originally Posted by aaronc7
Is this something dumb like a problem with the fuel pump? Log looks like a weak pump. Verify rail pressure.
Get a gauge on the schrader valve of the fuel rail and watch it while cranking.
Don't even need a gauge if you know what you're looking for, but it would be best. Stick a key or screwdriver tip in the schrader valve to release all the pressure. Turn the ignition on a few seconds, listen for the pump to prime, turn back off, and then open the valve again. If no high pressure spray (high pressure like gas shoots everywhere and you try not to get it in your eyes) then that's the problem.
Last edited by SiriusC1024; 06-08-2023 at 06:55 AM.
So rail pressure is at about 60 psi during cranking. I?ve even forced the pump on through the VCM scanner and it?s the same result. I guess some thing I?ve never considered, though was actual fuel volume. So I will check to see how much fuel comes out of the FPR with the key turned in the on position.
pull the rail with the injectors installed and see if they spray
Respectfully; The car starts and runs, it just shuts off after a few seconds
The only two possibilities I can think of:
- Fuel supply problem. Starting after extended cranking, running rough, then dying is classic bad fuel pump. Could be something fuel supply that's causing the same problem. Idk maybe something like the fuel filter element got overpowered by flow at WOT and now pieces are clogging the system or the regulator was damaged. Stranger things have happened. You're correct about pressure AND flow. Verify with a gauge that pressure is maintaineed when the car manages to run.
- Fuel injector timing is off. That's cam position sensor related.
What stood out in the log is the quick jump to 50% throttle, and the associated increase in MAP, wasn't matched by the injectors.
Patter matters but yeah I see your point. Still could have ruled out a few things such as a volume loss after a rotation or two of spraying. Possible stuck injector or two.
Well, we finally think we found it.
When this all occurred, we purchased a Russell ?6an one-way check valve and placed it right before the rail, to rule out the internal check valves of the three fuel pumps (factory in-tank, 2 Billet pumps with HOBS switches). What we were not tracking was how fast the pressure, and thus volume was falling off at the Turbosmart FPR 2000 regulator. So long story short, the diaphragm in side the Turbosmart regulator failed, bleeding off all pressure back to tank, since it is after the rail. We were keying on and cranking right away, and the in tank pump was not able to keep up beyond the first spray of fuel.
I confirmed this by placing the check valve in backwards after the return hose to force the car to rely solely on the in tank regulation pressure/feed (which after hours still held pressure). The car no starts and runs immediately, responds to all throttle input.
We?ve order another FPR, and I?ll update again once we confirm it keeps running.
I want to thank you all again for helping me shift my focus toward this.
Called it
Good find hope the rest goes smoothly.
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