PMO fuel gauge adjustment????

[irl]

So after an engine/ new fuel lines/pierburg install, the car is running but idling pretty high and the the PMO shows no pressure reading. I haven't adjusted the needle valve but I thought I would see an immediate high pressure before I do anything???

[Gordo2]

Your Pierburg is factory pre-set to a certain PSI (~ 5 for low pressure carb configs). Pierburg specs for their various pumps:
http://download.ms-motor-service.com/ximages/pg_pi_0034_en_web.pdf

Looks like you have a recirculation circuit coming from the PMO reg, which is generally acknowledged as a good thing.

Opening the PMO valve allows the fuel to recirculate back to the tank thereby reducing pressure. Good news - it looks like you don't have any blockage on your return line (0 psi indicating the fuel is recirculating to the tank with no back backpressure). Surprised your engine idles at very low pressure.

I use a small washer to turn the valve - play around with it until you get it to 3.5 PSI.

Good luck,

Gordo

[G50911]

my 68 doesn't have a return and i just capped it. i get a steady 3 psi. since this disables the valve does anyone know which pierburg pump gives out a constant 3.5? sorry to hijack your thread Siri

[irl]

Ok, thanks Gordo. Ill starting cranking it down and watch what happens. Assuming my pump is putting out 5 PSI, I expected the gauge to show a higher PSI and cranking it down would drop the pressure. Also odd that not only is the car idling, its idiling high with the idle screws way down. I do need to adjust the carbs though, they are newly rebuilt as well.

[irl]

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