five7kid

iTrader: (14)

Vehicle is '91 Bonneville 3800. Had 80k when purchased 2.5 years ago, has never retained fuel pressure when engine is shut off (don't have to relieve pressure when changing fuel filter, for instance). Replaced the fuel pump last year (was losing power when hot), runs well with new pump but was hard to start both before & after replacement. I've noticed it does not have any pressure at the rail after sitting over night or even immediately after shutting it off. I replaced the regulator (no change), it gets good mileage and otherwise runs great.

The fuel pump supposed to have a check valve, correct? Is it possible both the original and replacement pumps had bad check valves?

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82 Berlinetta, orig V-6 car, now w/86 LG4/TH700R4. 2.93 limited slip. Cat-back from '91 GTA, Accel HEI SuperCoil. AMSOIL syn lubes bumper-to-bumper. Daily driver, work-in-progress (LG4 w/'87 LB9 block, ZZ3 cam and intake, World 305 heads, Hooker headers & y-pipe, 3" Catco cat & 3" cat-back).
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Guest

Yea the pump is supposed to prevent the fuel from flowing back into the tank. Anything is possible with parts, so its hard to say if thats it or not. Are the injectors possibly leaking? That or the 'new' regulator is bad.

five7kid

iTrader: (14)

I doubt it's a problem with the injectors, as it idles & runs well once it starts, gets good gas mileage, and the fuel pressure is gone in the time it takes to turn the engine off and run up to the engine and check it. The new regulator didn't change a thing.

I didn't mention that I also changed the fuel pump relay. Would a lack of pressure when you first go to start it make it hard to start? It usually takes 3 or 4 tries, no matter how long you crank on it each time, before it starts. Really weird.

Sounds like I may be dropping the tank again. Oh, goodie!

ede

i'd look for a leaking injector or FPR leaking off preasure. just a guess, i'm not EFI expert.

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