Fuel Pressure - Team Camaro Tech
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post #1 of 5 (permalink) Old Jul 12th, 01, 03:50 AM Thread Starter
Join Date: Apr 2001
Location: Houston, TX
Posts: 10

I have a 454 L29 Crate Engine with a 4 barrel Holly 750 Double Pumper and Holly blue fuel pump (no fuel pump boss). The previous owner had the fuel pump mounted upside down and the thing was cavitating & failed shortly after I bought the car. I replaced the pump a regulator. Now the fuel pressure is not controlling properly. It starts out high at around 9 psi and drops to below 6 psi after driving a while. A few times it dropped to around 3 psi, and I closed the regulator, but could not increase the pressure. I changed out the carburetor, and that didnít help, I made sure there were no kinks in the line, replaced the fuel filter. The pressure gauge is mounted on the line going to the secondary bowl down stream of the regulator. When I punch the gas, the pressure does not change. I have checked the grounding of the pump and it is getting 12 volts. The pump is wired through the fuse block i.e. no relay is used. Any ideas/suggestion are appreciated.
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post #2 of 5 (permalink) Old Jul 12th, 01, 04:20 AM
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Location: Accord, NY
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Can you relocate the gauge to the primary line feeding the carb ( after the regulator )? I'm not sure what effect you are seeing when you are measuring the pressure to the secondary bowl.

Rick Dorion
69 RS Conv,355,M20,4.10's
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post #3 of 5 (permalink) Old Jul 12th, 01, 06:54 AM
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Location: Meridian, Idaho
Posts: 321

Be sure the fuel lines not close to a heat source like the exhaust pipe. I have had a similar problem . The fuel was being cooked a little before it got to the carb. The pressure gauge would drop off after a while driving the car.

68 SS 396
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post #4 of 5 (permalink) Old Jul 12th, 01, 08:05 AM
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Location: Concord Cal. USA
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Is the gauge a straight mechanical or one of those with a diaphragm as a sender. I have seen those diaphragm give some really strange readings for no reason. If it does like you said the pressure doesn' drop when you get on it I would look at the gauge.

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post #5 of 5 (permalink) Old Jul 13th, 01, 04:00 AM Thread Starter
Join Date: Apr 2001
Location: Houston, TX
Posts: 10

The gauge is a mechanical liquid filled. The line does run relatively close to the exhaust, and that theory makes sense. I will reroute the lines and move the gauge to the primary. I will let you know how it turns out. Thanks!
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