fuel system woes, need help
09-26-02, 12:06 PM
#1
fuel system woes, need help
I am having trouble getting the car started after weeks of work, if I can't get it up and running by Friday Sevenstock is out for me.. I am stumped right now and need some advice on where to look. Here are the Cliffs notes to get everyone up to speed:
Originally went in to do a turbo replacement procedure (originals had 97k and were leaking oil), I had previously had a hunting idle once in a while so I decided to remove the UIM and LIM as well to check the gaskets out and do a hose job. While doing this I figured it also made sense to take the injectors out and get them cleaned at RC, I also drilled and tapped the rails for NPT/AN fittings. Fabricated all my own SS lines and fittings, removed the pulsation dampener, mounted an Aeromotive FPR and ran all the lines through that. So I had the hose job done (99% sure I have everything in the right place, studied the diagram very closely), new turbos mounted, everything ready to go.
Here is where I ran into trouble, first pressure test I jumpered the fuel pump on and bingo.. sprung a leak on one of the rails where I had installed an NPT fitting. Removed that, tightened up the fitting, reinstalled. Pressure test #2 went ok, I adjusted it up to 38psi roughly with no detectable leaks. Reinstalled the UIM/throttle body, attempt to start the car.. no luck, just cranks over and over but would not start. I decide to pressure test again w/o the motor on, jumper the pump, pressure shoots up to 38psi quickly.. ok I think. I pull the jumper wire and now notice that the fuel pressure is slowly dropping immediately, falls back to 0psi within 10 seconds. Damn I think, it is not holding pressure somewhere.. but where? I remove the UIM again, pressure test, no external leaks anywhere. Hmm, I figure that the 850cc injectors I installed in the primary rail are not sealing and are flooding the motor. I take those back out, put the original 550cc injectors back in and decide to worry about an injector upgrade later. Pressure test #3 checks out, shoots up to 38psi.. I pull the jumper wire and the pressure stays up for much longer now.. but still falls back to 0psi within a couple of minutes. Shouldn't it stay at 20psi or so even overnight? I saw screw it and try to start it, I perform the anti-flood procedure (floor the gas before you crank it) a couple times, then try a real start. Well I got it to start, but I can't keep it running.. it sputters to life for a few seconds and just dies no matter how I modulate the gas pedal. By this point I am quite frustrated, I check the fuel pressure gauge when I get out and it is back to 0psi.. somehow the fuel pressure is not being kept up. So I am stumped, the fuel pump is a nearly new RP Denso unit, injectors have been cleaned, no external fuel leaks that I can see or smell. What could the problem be? I am beginning to point at the Aeromotive FPR unit but it checks out during testing.. I am close to my wits end after 3 weeks of work on this car. TIA, and sorry for the long post.
Matt
93 SSM
Originally went in to do a turbo replacement procedure (originals had 97k and were leaking oil), I had previously had a hunting idle once in a while so I decided to remove the UIM and LIM as well to check the gaskets out and do a hose job. While doing this I figured it also made sense to take the injectors out and get them cleaned at RC, I also drilled and tapped the rails for NPT/AN fittings. Fabricated all my own SS lines and fittings, removed the pulsation dampener, mounted an Aeromotive FPR and ran all the lines through that. So I had the hose job done (99% sure I have everything in the right place, studied the diagram very closely), new turbos mounted, everything ready to go.
Here is where I ran into trouble, first pressure test I jumpered the fuel pump on and bingo.. sprung a leak on one of the rails where I had installed an NPT fitting. Removed that, tightened up the fitting, reinstalled. Pressure test #2 went ok, I adjusted it up to 38psi roughly with no detectable leaks. Reinstalled the UIM/throttle body, attempt to start the car.. no luck, just cranks over and over but would not start. I decide to pressure test again w/o the motor on, jumper the pump, pressure shoots up to 38psi quickly.. ok I think. I pull the jumper wire and now notice that the fuel pressure is slowly dropping immediately, falls back to 0psi within 10 seconds. Damn I think, it is not holding pressure somewhere.. but where? I remove the UIM again, pressure test, no external leaks anywhere. Hmm, I figure that the 850cc injectors I installed in the primary rail are not sealing and are flooding the motor. I take those back out, put the original 550cc injectors back in and decide to worry about an injector upgrade later. Pressure test #3 checks out, shoots up to 38psi.. I pull the jumper wire and the pressure stays up for much longer now.. but still falls back to 0psi within a couple of minutes. Shouldn't it stay at 20psi or so even overnight? I saw screw it and try to start it, I perform the anti-flood procedure (floor the gas before you crank it) a couple times, then try a real start. Well I got it to start, but I can't keep it running.. it sputters to life for a few seconds and just dies no matter how I modulate the gas pedal. By this point I am quite frustrated, I check the fuel pressure gauge when I get out and it is back to 0psi.. somehow the fuel pressure is not being kept up. So I am stumped, the fuel pump is a nearly new RP Denso unit, injectors have been cleaned, no external fuel leaks that I can see or smell. What could the problem be? I am beginning to point at the Aeromotive FPR unit but it checks out during testing.. I am close to my wits end after 3 weeks of work on this car. TIA, and sorry for the long post.
Matt
93 SSM
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