C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

92 fuel pump question

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Old May 26, 2016 | 06:10 PM
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Default 92 fuel pump question

We gotta 92 that was just in a shop so their saying the pump is at around 20 psi and should be up around 40

The problem in question is sometimes when the cars been running and I shut it off leave for awhile and restart itll miss and and fart the couple minutes later it smooths out and runs fine............the problem doesn't happen often but does happen.

what I wanna know is why does the car start and run fine 90% of time if the pump is said to be going out and have that low of reading??

Last edited by lectroglide; May 26, 2016 at 07:22 PM.
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Old May 26, 2016 | 06:29 PM
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I have no idea what a 20% or 40% pump means. The question is: "can the pump maintain rated pressure under full load?" If yes, its good to go and if not, a new pump and strainer are in order. I'd say that you should find a shop with a pressure gauge that can be hooked up and read while the car is being driven and see if your set up will maintain about 41-47 psi. If not, the fuel system needs attention.

Last edited by 1984Z51auto; May 26, 2016 at 06:31 PM.
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Old May 26, 2016 | 07:30 PM
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Originally Posted by 1984Z51auto
I have no idea what a 20% or 40% pump means. The question is: "can the pump maintain rated pressure under full load?" If yes, its good to go and if not, a new pump and strainer are in order. I'd say that you should find a shop with a pressure gauge that can be hooked up and read while the car is being driven and see if your set up will maintain about 41-47 psi. If not, the fuel system needs attention.
.........typo

Last edited by lectroglide; May 26, 2016 at 07:32 PM.
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Old May 26, 2016 | 09:01 PM
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change the fuel filter
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Old May 26, 2016 | 09:08 PM
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Originally Posted by mtwoolford
change the fuel filter
and get a fuel pressure gauge on it.
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Old May 26, 2016 | 11:09 PM
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Originally Posted by riversidedan1
We gotta 92 that was just in a shop so their saying the pump is at around 20 psi and should be up around 40

The problem in question is sometimes when the cars been running and I shut it off leave for awhile and restart itll miss and and fart the couple minutes later it smooths out and runs fine............the problem doesn't happen often but does happen.

what I wanna know is why does the car start and run fine 90% of time if the pump is said to be going out and have that low of reading??
And what else have they done? Any fool can hook up a gauge and say "30 psi". If it were mine, first thing to check is if the fuel pressure hose were removed, does it smell of gas. If so, you have a ruptured fuel pressure regulator diaphragm and before I go anywhere, I change that. I would also crimp off the return line and see if it holds pressure. If it does, your regulator diaphragm might have issues.

When you cycle the pump and let the pressure bleed off, are the plugs wet with fuel? If so, time for the injectors to be serviced or replaced.

Could your pulsator be leaking? Hard to tell from here but if you clamp off the return line and the pressure drops and the plugs are dry, I would suspect the pulsator.

The low reading could be bad fuel pressure regulator, leaking injectors, leaking damper or a combination of all 3. Reason it runs well most times is that you are not always demanding full fuel volume and pressure.
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Old May 27, 2016 | 05:47 PM
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Originally Posted by aklim
And what else have they done? Any fool can hook up a gauge and say "30 psi". If it were mine, first thing to check is if the fuel pressure hose were removed, does it smell of gas. If so, you have a ruptured fuel pressure regulator diaphragm and before I go anywhere, I change that. I would also crimp off the return line and see if it holds pressure. If it does, your regulator diaphragm might have issues.

When you cycle the pump and let the pressure bleed off, are the plugs wet with fuel? If so, time for the injectors to be serviced or replaced.

Could your pulsator be leaking? Hard to tell from here but if you clamp off the return line and the pressure drops and the plugs are dry, I would suspect the pulsator.

The low reading could be bad fuel pressure regulator, leaking injectors, leaking damper or a combination of all 3. Reason it runs well most times is that you are not always demanding full fuel volume and pressure.
To tell ya the truth for $200 they didn't do much but your right about when I put my foot in it does bog down , BTW what does the "pulsator do?

Last edited by lectroglide; May 27, 2016 at 05:50 PM.
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Old May 27, 2016 | 06:02 PM
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Originally Posted by riversidedan1
To tell ya the truth for $200 they didn't do much but your right about when I put my foot in it does bog down , BTW what does the "pulsator do?
It connects your pump to the fuel line. If they leak you have a fountain in your tank and low fuel pressue.
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Old May 27, 2016 | 06:22 PM
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[QUOTE=antfarmer2;1592304355]It connects your pump to the fuel line. If they leak you have a fountain in your tank and low fuel pressue.[/QUOTE

ok thanx and am hoping after we pull the pump out that will be the culprit, but might as well get a new pump and replace the whole works

Last edited by lectroglide; May 27, 2016 at 06:24 PM.
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Old May 27, 2016 | 07:38 PM
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Start with the basic testing before we toss parts at the issue. If you have to, get a kit from Racetronix which will take care of the pulsator and get you needed new bolts and gasket with no trips to the hardware store or the dealership
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