Fuel Pres. 35#
02-11-2002, 01:49 PM
#1
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Fuel Pres. 35#
Car starts and runs for a few seconds then dies, and the fuel pressure varies between 35-42. When off, pumps up to 42, pump shuts off and pressure falls to 40 and holds. Only code is #24 vari speed sensor which I am assuming doesn't affect idle Changed fuel relay and fuel filter. Before you make my day and tell me it is the fuel pump is there anything else to consider?
02-11-2002, 02:08 PM
#2
Ray,
If your fuel pump will make 42 PSIG when priming, it is probably good. 35 PSIG is a little low, but still within the specified acceptable range of 37 PSIG, +/- 3 PSIG. If you want to test the pump, remove the pressure line and place it in a container suitable for gasoline. Run the pump for 15 seconds with a 12VDC power jumper in the 'G' terminal of the ALDL and measure the amount of fuel delivered. The pump should be able to free-flow ½ pint of fuel in 15 seconds or less. Most pumps will easily double that.
If the pump has an adequate output flow, you may want to temporarily increase the idle fuel pressure for testing, disconnect and cap the vacuum line to the FPR. Test the fuel pressure again with the engine running. Is that better? If so, you may have a failing or weak regulator and might want to look into converting to an adjustable FPR. Here are some instructions if you don't want to spend the cash on an aftermarket unit:
AFPR Conversion.pdf
If your fuel pump will make 42 PSIG when priming, it is probably good. 35 PSIG is a little low, but still within the specified acceptable range of 37 PSIG, +/- 3 PSIG. If you want to test the pump, remove the pressure line and place it in a container suitable for gasoline. Run the pump for 15 seconds with a 12VDC power jumper in the 'G' terminal of the ALDL and measure the amount of fuel delivered. The pump should be able to free-flow ½ pint of fuel in 15 seconds or less. Most pumps will easily double that.
If the pump has an adequate output flow, you may want to temporarily increase the idle fuel pressure for testing, disconnect and cap the vacuum line to the FPR. Test the fuel pressure again with the engine running. Is that better? If so, you may have a failing or weak regulator and might want to look into converting to an adjustable FPR. Here are some instructions if you don't want to spend the cash on an aftermarket unit:
AFPR Conversion.pdf
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