New engine. My fuel pressure is set to 40psi, 30psi with vacuum hooked up. When I shut the car off it jumps to 40 because of no vacuum with the car off... but then it drop to 35psi within a couple minutes. I never really watched it to see how fast or slow it drops from there but I do know that the next day when I go outside the fuel pressure guage says 0psi. Is this normal for it to drop to 0psi over night.... I think I heard somewhere that it is ok. But how fast or slow should the fuel pressure drop. If it does drop too fast what could be the cause of it?? I have new adjustable fuel pressure regulator and cleaned and flowmatchec 24# LT1 injectors with all new screens and o-rings.

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1986 Trans AM
355 TPI
4 Wheel Disc Brakes
9 bolt Borg Warner Rear (2.77's....oh joy) :P
6" rods, approx. 9.7:1 Compression, Stock TPI (soon to be ported), 24#/hr LTI injectors (cleaned and flowmatched by Cruizin Performance), Hedman Shorty Headers, 3" exhaust with 80 series flowmaster, SBC 993 heads completely redone and modified for 1.6 RR, 1.52 RR (for now), Comp Cams XE262-14 TPI Cam, Holley AFPR, TPIS airfoil, MSD wires, MSD 6-AL Ignition, Hypertech 53,000 volt coil.

Track times to come.

 

I cant speak for others, but my fuel pressure stays within 10psi after sitting all night. Your problem sounds like a leak somewhere. Maybe an injector or bleeding back through the fuel pump. Just my opinion....

Kevin

 

Well what the heck would cause that?? I got brand new o-rings on my injectors so I can't figure out where I could possibly have a leak. Bleeding back through the fuel pump?? how??




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1986 Trans AM
355 TPI
4 Wheel Disc Brakes
9 bolt Borg Warner Rear (2.77's....oh joy) :P
6" rods, approx. 9.7:1 Compression, Stock TPI (soon to be ported), 24#/hr LTI injectors (cleaned and flowmatched by Cruizin Performance), Hedman Shorty Headers, 3" exhaust with 80 series flowmaster, SBC 993 heads completely redone and modified for 1.6 RR, 1.52 RR (for now), Comp Cams XE262-14 TPI Cam, Holley AFPR, TPIS airfoil, MSD wires, MSD 6-AL Ignition, Hypertech 53,000 volt coil.

Track times to come.

 

I have new injectors and new fuel pump and by morning my pressure is at 0

 

Well it's good to know I'm not the only one with this problem. Or maybe it's not a problem at all. Heck, I don't know.


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1986 Trans AM
355 TPI
4 Wheel Disc Brakes
9 bolt Borg Warner Rear (2.77's....oh joy) :P
6" rods, approx. 9.7:1 Compression, Stock TPI (soon to be ported), 24#/hr LTI injectors (cleaned and flowmatched by Cruizin Performance), Hedman Shorty Headers, 3" exhaust with 80 series flowmaster, SBC 993 heads completely redone and modified for 1.6 RR, 1.52 RR (for now), Comp Cams XE262-14 TPI Cam, Holley AFPR, TPIS airfoil, MSD wires, MSD 6-AL Ignition, Hypertech 53,000 volt coil.

Track times to come.

 

I have replaced my injectors and o-rings and watch my fuel pressure drop to zero in about an hour. I thought something was odd with it so I pulled the injector rail out, turned key to get pressure up and no injector leaks but I had the same pressure drop. Keept me confused for a while but I have no problems idling or at high RPM's so I put it together and I don't worry about it.

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87 Black on Black T/A
T-Tops Digital dash
5.0 TPI S/R Torquer 305 heads Summit TPI cam
204/214 @.050 .420/.442
SLP headers and catback
A4 with 3.42 gears
Fully loaded and everything usually works.

 

Sound good.

 

i have also heard that these fuel systems are supposed to relief fuel pressure as soon as u turn the key off, according to the chiltons manual.

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- David
88' GTA 5.7L TPI MODS---> air foil, K&N, Shift Kit, 180* therm, TB bypass, Gutted CAT, Flowmaster 80 Series Muffler added to Unkown CatBack, Ported Intake

http://www.geocities.com/david_angel_16