Good fuel pressure?

Nixon1 · 04-20-2003, 07:43 PM

Bought the tester today. After the car had been sitting overnight, I had my dad turn the key for me and watched the gauge. It spiked up but then dropped back to only 20 psi and held steady. So he turned the key back and primed the pump again...shot up to a 'normal' reading for this car. Relieved pressure in the pump to bring it back down to zero, and primed it again....didn't have any more low psi problems, but first, is that any sort of warning sign? 20 psi is pretty low...

After it started working fine...with the fuel pump priming, it was at about 42 psi. KOEO, with the pump having already primed, it read about 36 psi. With the engine running, even though it was cold we flinched the gas pedal to bring the idle down to a slow one, and it read about 34 psi. Tapping the gas lightly caused only a loss of 4 psi or so.

So, is it operating normally? Thanks guys.

lx mike · 04-20-2003, 08:16 PM

It's fine. fuel pump primes for those few second then shuts off till car is running. when running fuel pressure should be around 32-34 psi with vacuum line on the regulator, with it off around 38-39 psi with engine running.

04-20-2003, 07:43 PM	#1
Nixon1 Registered Member Join Date: Jan 2003 Location: Palm Bay, FL Posts: 432	Good fuel pressure? Bought the tester today. After the car had been sitting overnight, I had my dad turn the key for me and watched the gauge. It spiked up but then dropped back to only 20 psi and held steady. So he turned the key back and primed the pump again...shot up to a 'normal' reading for this car. Relieved pressure in the pump to bring it back down to zero, and primed it again....didn't have any more low psi problems, but first, is that any sort of warning sign? 20 psi is pretty low... After it started working fine...with the fuel pump priming, it was at about 42 psi. KOEO, with the pump having already primed, it read about 36 psi. With the engine running, even though it was cold we flinched the gas pedal to bring the idle down to a slow one, and it read about 34 psi. Tapping the gas lightly caused only a loss of 4 psi or so. So, is it operating normally? Thanks guys. __________________ '91 Mustang GT 5.0 AOD Daily Driver Current stats: NEW 302 short block, E-303 cam (@.050, 220/220, .498/.498, 110 degrees), 1.6 roller rockers, Performer RPM heads (aluminum, 1.9/1.6, 60cc chambers), Cobra intake, Granatelli 75mm MAF, Billet AFPR, Equal-Length Shorty Headers, Off-Road X Pipe, Flowmasters, 4.10 POSI 13.73 at 103.8, ~2.2 60'

04-20-2003, 08:16 PM	#2
lx mike Undescribable Join Date: Sep 1998 Location: Ft Myers Fla Posts: 1,539	It's fine. fuel pump primes for those few second then shuts off till car is running. when running fuel pressure should be around 32-34 psi with vacuum line on the regulator, with it off around 38-39 psi with engine running. __________________ Rice Haters Club Member #101

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