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[bmacf]

Hey everyone, I need a little help on what looks to be a fuel pressure problem. I have Megasquirt, but I'm thinking this is either a fuel pump or pressure regulator issue. I have a fuel pressure gauge on the fuel line before the fuel flows to the fuel rail. I seem to recall it's always read around 37psi, but I thought I'd check things out because my engine sounds like it's missing a cylinder (note: leakdown test sais everything is ok).

A week ago when it started to run poorly I noticed the fuel pressure at idle was down around 32psi. Later it was at 37psi so I wrote off fuel pressure as an issue.

This weekend the engine was running worse so I looked at fuel pressure again. At idle its 37 psi, but if I blip the throttle the fuel pressure drops down to 32 psi.

This isn't normal, right? Fuel pump or fuel pressure regulator?

Thanks,
Bill

[Mats]

It used to be 37psi always?
That sounds really wrong to me, don't you have a vacuum line to your fuel pressure regulator? The pressure differential across the injector should be constant and therefore the fuel pressure will follow plenum pressure, i.e. fluctuate quite a bit.

[bmacf]

OK, you got me on that one. I guess whenever I looked, it was 37psi. I never did the blip the throttle test though.

Can I interpret your response to mean the phenomena that I'm seeing is normal?

Thanks,
Bill in Maryland.