LT1 Based Engine Tech 1993-1997 LT1/LT4 Engine Related

Low Fuel Pressure

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Old 04-10-2009, 04:05 PM
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Low Fuel Pressure

Cars been running like a dog. Pulled spark plugs, noticed they were white. I'm leaning out.

Put a fuel pressure gauge on the car and I'm getting 25 PSI at idle and with the FPR vac line disconnected.

The fuel pump is a 3-4 year old Walbro 255.

I'm thinking the pump might be bad, but is there anything else that can cause this? The fuel filter has never been replaced to my knowledge, but I can't see that causing a 20 PSI drop in pressure.

Any input would be appreciated.
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Old 04-10-2009, 04:08 PM
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May as well replace the filter, they're $5 and take 10 minutes to change.
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Old 04-10-2009, 04:26 PM
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Originally Posted by silentsprintero
May as well replace the filter, they're $5 and take 10 minutes to change.
You're right, I'm going to do that right now. Will post up when I get done.
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Old 04-10-2009, 05:19 PM
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Problem solved.

I was happy when I tried to pour the gas out and it was dripping slowly and black with a lot of dirt particles in it. It made me think that this could actually be the problem.

The car feels like new, but the pressure gauge is only showing 30 PSI, but it's steady, not like before where it was at 25, and would slowly creep down to 20-22 psi.

It's holding very steady at 30 and not fluctuating. This is a $15 harbor freight gauge that I just picked up today. I wonder if it's the problem, or if the pressure is actually very low.

$8 fix is always nice.
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Old 04-10-2009, 05:57 PM
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That's still low. Is there any fluid under the vacuum line to the FPR?
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Old 04-10-2009, 06:05 PM
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Originally Posted by silentsprintero
That's still low. Is there any fluid under the vacuum line to the FPR?
No.

I'm thinking I might have a faulty gauge. This is the one I picked up.

http://www.harborfreight.com/cpi/cta...emnumber=92699
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Old 04-10-2009, 07:48 PM
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Originally Posted by raroz28
No.

I'm thinking I might have a faulty gauge. This is the one I picked up.

http://www.harborfreight.com/cpi/cta...emnumber=92699

Not a very quality piece....Adaptors and hoses are OK, but not the guage... Get what you pay for...

Just go to Sears and get one for 30~40 dollars... Thats what I have ben using for acouple of years now with no issues....
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