Fuel pressure loss?

[jan]

Hi all,

My first post on grandprixforums! Thank you all for this very helpful site.

I have a '98 Grand Prix GTP. I noticed that after the car is off for ~8 hours, there's no longer any fuel pressure at the Schrader valve on the fuel rail. I didn't think much of this as the car was still starting fine.

However, the fuel pump recently went out and I went ahead and replaced both the fuel pump AND the fuel injectors with new OEM (Delphi, Bosch, respectively) components.

This got me curious - surely it was one of those two that was causing the fuel pressure loss, right?

But when I tested the Schrader valve again today, it had still lost all fuel pressure after ~8 hours.

Is this loss normal? Or is there some other component that could be causing this fuel pressure loss over time? The car runs well, no OBD codes, scan tool gives sensible data, and I do not see or smell fuel or observe any loss in fuel tank level over time.

Thank you!

-Jen

 

[mguzzo]

could be the checkvalve in the pump is back-leaking.
It really doesn't matter, just key-on and wait for the pump to prime for two seconds.

 

[Scottydoggs]

yes normal for the fp to drop over 8 hrs sitting.

 

[Fivefingerdeathpunch]

It should only hold fuel pressure for maybe 5-10 minutes and not hours.

This is why when you turn the key to the on position it primes the fuel system for 2 seconds.

 

[jan]

Okay, understood. Thank you very much mguzzo, scottydoggs, and Fivefingerdeathpunch!