Fuel pressure at power setting?
09-25-2003, 11:05 AM
#1
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Location: Dayton Ohio
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Fuel pressure at power setting?
I installed a hi-pressure walbro fuel pump and was just wondering if my pressure at idle being at 42psi and my pressure at 3000 rpms being 40 psi is a little low?? My fuel filter is new. Does that seem normal? The car runs great but right now it is running a little rich. thanks for your opinions! 
09-25-2003, 11:21 AM
#2
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Since the fuel pressure regulator is "vacuum compensated", the fuel pressure is dependant on throttle and RPM. At WOT, the fuel pressure should rise to the "no vacuum" value (41-46psi specified) and stay there all the way to red line. Testing at 3,000rpm isn't meaningful.
Start the car, let it idle, and pull the vacuum line off... that is the "no vacuum" value. Put the vacuum line back on, and the pressure should drop 5-8psi, depending on your cam. Then at WOT (on the road, under load), pressure should return to the "no vacuum" level.
Start the car, let it idle, and pull the vacuum line off... that is the "no vacuum" value. Put the vacuum line back on, and the pressure should drop 5-8psi, depending on your cam. Then at WOT (on the road, under load), pressure should return to the "no vacuum" level.
09-25-2003, 11:28 AM
#3
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Thanks for the info I'll give it a try. I think that everything is fine It just seemed to be a little on the low side. I thought maybe the fuel pressure regulator may be a little clogged or be going on its way out. thanks againl.
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