Fuel PSI Readings

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Jun 10, 2008 | 09:22 PM

CENTURION

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Fuel PSI Readings

I have an 88 I suspect has a few leaky injectors, fuel PSI is around 42, then drops to 20 PSI, 10 min or so after shut down. What is typical for a car with a normal functioning system?

Thanks.

Jun 10, 2008 | 10:38 PM

John A. Marker

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From: Dublin CA

I tested my 1985 FP about a week ago suspecting a leaking injector. Here were the results (started at 38 pounds):

38 psi starting pressure
34 psi 1:45 minutes
32 psi 3:34 minutes
30 psi 18:42 minutes
27 psi 60:00 minutes
24 psi 1-1/2 hrs
22 psi 2 hrs 17 min
20 psi 3 hrs
20 psi 3 hrs 20 min
9 psi 11 hrs
6 psi 23 hrs

I would have expected the pressure to drop to 0 within 20 minutes or less with a bad injector. When I had a bad check valve in the fuel pump, it would drop to 0 with 2 minutes or less.

Jun 10, 2008 | 10:53 PM

65Z01

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From: SE NY

Cruise-In II Veteran

It sounds like a little quicker bleeddown than usual but not excessinve.

What are the symptoms that suggest leaking injectors to you?

Jun 10, 2008 | 11:25 PM

Aggravated4life

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If you can pinch off the return line at the tank,you can do another test and see if it still drops as much.

The CS injector can be leaking as well.

Also,if your handy at fixing your own cars,take the TPI plenum and runners off and pop the fuel rail out of the intake,but leave it hooked up the to the gas lines.DO a fuel pressure test on a cold engine,have alot of rags ready.Check the CS injector if eqiupped and see if its leaking gas too.

Do any of the 8 Injectors leak gas during the gauge test? Injectors should not leak a drop of fuel...if any of them are dripping gas,even in droplets,the injector(s) is bad.ALso,check the regulator...there should be no gas coming out of it or inside the vacuum hose.

Jun 10, 2008 | 11:55 PM

coupeguy2001

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From: Phoenix AZ

2021 C4 of the Year - Modified Finalist

injectors

If the injectors are leaking, the engine will be running poorly for the first minute after sitting for half hour.
If it doesn't run bad, I would suspect the FPR or the fuel pump check valve, or the pulsator is bleeding off your pressure.
My pulsator was leaking fuel when I used a borescope to inspect the tank for debris. I could watch the fuel running down the tube.

Jun 11, 2008 | 03:20 PM

AGENT 86

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From: Summerland B.C. Canada

You need to isolate the area of pressure loss.
http://members.shaw.ca/corvette86/Fu...mDiagnosis.pdf

Jun 11, 2008 | 06:00 PM

CENTURION

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Quote:

Originally Posted by 65Z01

It sounds like a little quicker bleeddown than usual but not excessinve.

What are the symptoms that suggest leaking injectors to you?

Thanks for the replies, it has the symtom of starting up and running great when cold, than after warm it cranks a lot longer, and you can smell the fuel in the exhaust. I'm thinking of having a FPR put on the same time as injectors. The car runs really well the first 10 min or so of driving, I'd like to get it that way consistently.

Jun 11, 2008 | 09:22 PM

the blur

Melting Slicks

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Posts: 2,775

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From: cyberspace NY

20 years old, yank it apart, and replace the FPR and injectors.
You can't feel bad and throwing parts at a 20 yo car.

I did injectors, EGR, IAT, o-rings, everything except the FPR.
glad I did.