Jon Betts

1987 944NA

after rebuiding the engine and correcting many "strange things" The car now will not idle correctly. So I check the fuel pressure at idle the gauge is pegged at +80psi. So I change the FPR to an adjustable one, pressure is still pegged at +80psi with it turned all the way down. Removed the fuel return line from the FPR and it is completly blocked? Does this line have any valves in it or does it just go straight back to the tank? I also dont undertand how the car would run at all with 80psi fuel pressure I thought the injectors cut out if the pressure was too high?

Thanks

Mike C.

Hi Jon,

I'm pretty sure the fuel return line goes straight back to the tank. Also, I don't believe there is any over-pressurization shut off. The high pressure will make your engine run rich since the DME assumes flow based only on duration of the injector opening and a prescribed pressure across the injector. If the pressure is higher than spec, more fuel flows per unit time. Is it possible you crushed the return line with a misplaced jack?

PorscheG96

The injectors should be cutting out at that fuel pressure. My car wouldn't idle for more than 30 seconds when the fuel pressure spiked like this. Replacing my fpr and damper fixed the problem, not sure if yours is identical though. Good luck!