Fuel Pressure Stability

cwmcobra · #1 (**permalink**) 04-02-2003, 08:00 PM

Any experiences with fuel pressure fluctuation with operating temperature? I'm using an Aeromotive fuel system on my Ford 514 V8 with a Holley Street Avenger 870 CFM carb. When I start the engine cold and adjust the fuel pressure regulator to 7 PSI, per Holley spec. as the engine warms up the pressure drops to below 3 PSI. Doesn't seem to be impacted by engine speed. Same readings at idle or 2000-3000 RPM. Is this normal? Should I suspect a bad regulator? Or could it be a faulty engine builder (yours truly)?

Thanks!

Chuck

aumoore · #2 (**permalink**) 04-02-2003, 08:27 PM

Try adjusting the fuel pressure after the engine reaches operating temp. Also check your fuel line for any obstruction like maybe silicone that some idiot used to seal the fuel tank. Dont ask me how I know such things.

cwmcobra · #3 (**permalink**) 04-02-2003, 08:30 PM

The fuel cell has yet to be fabricated, so that's not the problem. Just sucking fuel from a 5 gallon jug at the moment. I'll probably deal with a fuel cell problem later!

I've emailed Aeromotive to get their suggestions as well.

Thanks,

Chuck

Cobra20646 · #4 (**permalink**) 04-03-2003, 07:04 AM

Chuck,

A few months ago I was at a loss to figure out why my fuel pressure was erratic...... was fine when first started, but went crazy after the engine warmed up the under hood temps,... turned out to be a bad pressure gauge, so don't rely on yours unless your sure it's right!

- Jim -

cwmcobra · #5 (**permalink**) 04-04-2003, 05:21 PM

To close the loop on this question, Jim, it appears you have right answer. Here's the response from Aeromotive to my tech question:

Chuck,

I’d bet dollars to doughnuts that you have a liquid filled gauge. This is a common problem, as these gauges seem to change their reading approx 3-5 psi from cold to hot, with the cold reading being the higher and correct pressure. To test, take a heat-gun or blow dryer and, with the fuel pump running and engine cold but idling, heat the gauge gently but rapidly. Let me know what you find.

Brett Clow
Aeromotive Tech Dept

You guessed it.......I have a liquid filled gauge. Can't figure out why I paid more for the liquid and have this type of problem. Ignorance is no excuse!

Guess it pays to ask the experts. Jim, I'll include you in that group now.

Thanks,

Chuck