Fuel pressure drops then stalls

Littleloogy said:
I don’t want to know how much money you threw at this problem. Lol

Unplug you MAF and give it another go. (Force your Car into closed loop) see if it’s boost leak related.

It’s got to be something simple, like a loose ground or something. Especially if it runs and dies.


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So far, everything I replaced was bad so I'm not even mad. ITFP was probably ok but the filter wasn't and I saw no point in going through all that and reusing the old pump. HPFP was given to me by a very good friend. Resistor was shot. Relief valve was the biggest improvement though since I can now get it to 1k psi while cranking it and flooring the gas. Replacing all 4 of the blue relays tomorrow.
 
Still no Codes? Sometime fault codes will be stored in the PCM and not illuminate the CEL
 
Littleloogy said:
I don’t want to know how much money you threw at this problem. Lol

Unplug you MAF and give it another go. (Force your Car into closed loop) see if it’s boost leak related.

It’s got to be something simple, like a loose ground or something. Especially if it runs and dies.


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I have no clue how running with the maf disconnected would tell me whether or not I have boost leak

So, I replaced all 4 of those blue relays with brand new relays. It ran like a champ for a long time, long enough to get coolant temps to 138 is this 40 degree air and then it died again. LTFT /STFT is at -0.16
 
Tommy said:
I have no clue how running with the maf disconnected would tell me whether or not I have boost leak
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It forces the ECU into closed loop. So if you have an abnormally huge leak somewhere like the PCV hose popped off and the intake was sucking a bunch of unmetered air, than the car would run. Had to do this to get home one time. Ran like shit, but I got home.

I was just throwing idea’s out there to try to help get her going. Not a proper way to diagnose a problem, I will admit. Sounds like your on the right path.


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Maybe this?
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Sounds like an electrical issue if the car will run and then just randomly die. Try wiggling the wiring harness going into the fuse block while the car is running. If it ran for a while after you replaced the relays, maybe you disturbed a poor connection there. I know someone else around here had a bad connection on the underside of the fuse block where the harness goes into it.
[doublepost=1509573247][/doublepost]He determines that it was a bad connection at the resistor connector
 
I saw that. He had no 12v at the Circuit relay. I tested both the circuit and go spot and they both have juice. Going to try the primary o2 tonight but definitely open to other suggestions.
 
This is the one where they determine that the connection on the bottom of the fuse block at the harness was bad. You could try the jumper just to be sure.
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[doublepost=1509574412][/doublepost]If your Primary O2 is bad, it won't cause the car to die, the PCM will just run the engine excessively rich. Are you certain you don't have a large vacuum leak? If you keep disconnecting the battery the Fuel trims will reset giving you misleading information. If you can get it to stay running for a minute, try spraying the intake plumbing (Intake, turbo inlet, intercooler plumbing, intake manifold) after the MAF with brake cleaner. You will hear the engine increase RPM if it sucks the cleaner in anywhere. Sometimes loose clamps or cracks will open and close with vibration and engine movement.
 
Yeah, thats Jordie. Spoke with him too. Unfortunately, not the same issue. I put a jumper on both the fp and the circuit relay with the same results. Now, interestingly enough, it idles and revs like a champ until the temps hit 140 then it dies as if on queue. I could try what you are suggesting but does it have to be brake cleaner? Will electrical contact cleaner work too?
 
it has to be something flammable, so carb cleaner or brake cleaner. Otherwise the engine wont burn it and you won't hear/see the increase in RPM. You can also do this while viewing STFT's on your Accessport. If you have a leak, the STFT's should go towards lean (+ trims) then when you spray the cleaner and it gets pulled into the engine, the O2 sensor will see the additional fuel and pull fuel away (- trims).
[doublepost=1509631335][/doublepost]Also, keep checking for codes periodically and don't disconnect the battery anymore. If you can keep it running until the coolant temp hits 140, leave the key in the run position when it dies and immediately scan for codes. Are your cooling fans going Ape shit? Like running hyper speed when the car shuts off?
 
SheepDog said:
it has to be something flammable, so carb cleaner or brake cleaner. Otherwise the engine wont burn it and you won't hear/see the increase in RPM. You can also do this while viewing STFT's on your Accessport. If you have a leak, the STFT's should go towards lean (+ trims) then when you spray the cleaner and it gets pulled into the engine, the O2 sensor will see the additional fuel and pull fuel away (- trims).
[doublepost=1509631335][/doublepost]Also, keep checking for codes periodically and don't disconnect the battery anymore. If you can keep it running until the coolant temp hits 140, leave the key in the run position when it dies and immediately scan for codes. Are your cooling fans going Ape shit? Like running hyper speed when the car shuts off?
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If there is a boostleak, I'd say it is at the tmic itself. I have had all piping off since I started this, intake to tip, tmic to throttle. Possibly bpv too, I'd guess.
No fans at all but 140 would not be enough to set them off.
 
Yeah, I mentioned the fan thing because if the coolant temp sensor or T-stat is having an issue, the coolant temp may not be accurate, which could point towards a blown head gasket. Small vacuum leaks certainly wouldn't cause the engine to die, just run lean so it would have to be a massive leak to kill the motor. When you are monitoring fuel pressure while the engine is running, does it fall off gradually before the engine dies, or does the engine just die with no pre-warning from loss of fuel pressure?
 
While it build up toward that temp, the PSI looks great. This take maybe 10 minutes to get up to it right now. It is no instant but the drop takes all of 30 seconds or so before it dies.
 
I was just trying to determine if the loss of fuel pressure was actually causing the engine to die, or if some other electrical issue was going on. So when you are viewing live data, does the fuel pressure start to go down just before the engine dies or is the fuel pressure at normal (430 psi or so) when the engine dies?
 
Have you tried removing the resistor from the equation? Unplug it and jumper the two wires together. Still no codes?
 
I tried it on the circuit relay and then the fp relay - same result. Still no codes.
 
And you verified voltage on both relays even when it won't run? I thought maybe the resistor might be getting too hot and crapping out.
[doublepost=1509673929][/doublepost]Another way you could be certain that it's an electrical issue related to fuel pressure is to monitor voltage right at the ITFP connector. If you still have voltage when it dies, then I would be looking for a mechanical issue.
 
Have you replaced the crank position sensor? I had an issue with my car last year where it'd die whenever it felt like it and then would just crank and only fire up when it wanted. Ended up being the crank position sensor and never threw any codes
 
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