Fuel Pressure Loss (Page 1/1)
Notamechanic APR 16, 03:50 PM
I've read in other discussion posts that the fuel rail should hold fuel pressure for a while. When I prime the pump, the fuel pressure hits 45 psi then drops to zero within 10 seconds. I have installed a new regulator, fuel pump, and double checked the new injectors are working.

I pulled the return line to the tank then primed the fuel rail, fuel came rocketing out, So I guess that's where the fuel pressure is going? It constantly dumps fuel when trying to start as well.

Is there something I am missing? Was the new pressure regulator bad? Could a vaccum leak cause this? I don't hear any hissing and all the vaccum lines are new.

Any tests or ideas where to start? All help is appreciated.
sleek fiero APR 16, 05:21 PM
if your pressure regulator is working you will get return fuel . I suspect your pulser is leaking or the rubber fuel connectors to the pulser are leaking. I eliminated the pulser on mine with a piece of proper in tank fuel line and have no more fuel pressure loss. The pulser is there to supposedly quiet the pump and reduce shock load on the system but lots of cars are running just fine without it. sleek
sanderson231 APR 16, 09:55 PM
This is a sign that the fuel injectors are weeping even though they are powered off. They probably need cleaning.

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formerly known as sanderson
1984 Quad 4
1886 SE 2.8L
1988 4.9L Cadillac
1988 3800 Supercharged

sleek fiero APR 17, 01:31 PM
I think that if one or more injectors bled off 45 lbs of pressure in 10 seconds or less the car would not run or run like a bag of crap . It would probably smoke a lot as well. I would try deadheading the fuelpump on the fuel rail feed line with a test gauge to see if it still drops. Be careful to only momentarily key the pump because you are bypassing the regulator. At least this will avoid messing with the injectors if they are not the problem.
Notamechanic APR 23, 04:22 PM
The car refused to start. Fuel pressure is 45 while cranking.

I dropped the tank and deleted the pulsator. Didn't seem to change a thing. Fuel pressure still drops to zero within seconds of turning off key.

The smallest squirt of starting fluid and the car immediately started and idled. Fuel pressure maintained in the 40-42 range while running.
theogre APR 23, 04:44 PM
Noid light to test if ECM is even turning them on.

EFI won't start if have ignition problems or ECM or wires are "bad" and ECM thinking Ignition does not run.

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Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave