Fuel Pressure question

[NC325iC]

Alright heres the current situation, ive just installed an adjustable fuel pres reg and gauge from IE, first off if you get one mine came pre set to about 80psi so yeah, second i get a good pres reading when running but as soon as you shut the car off it just drops.

in my old setup with a separate gauge on the feed line the pressure would kinda slowly go down. I have recently heard a couple of whines from my fuel pump on startup so it looks like thats gonna need a replacing pretty soon.

so, is this pressure drop due to the location of the gauge or could it be my fuel pump check valve (or whatever they call it in fuel pump language)?

edit: also, where the hell did others mount their afpr? mine is mounted to the bracket for the diagnostic plug, it took me a long time and some bracket bending and grinding to figure out where to mount it. Id say thats where most of my time doing this came from.

[jlevie]

I'd say the gauge is in the right location since you see normal pressure with the engine running. Unless the return line to the tank has a serious obstruction, you wouldn't see pressure on that side.

The one-way valve in the pump could be bad, or the regulator could be allowing pressure to drain through it. You should be able to figure out in which direction the drain down is occurring by jumppering the fuel pump relay and pinching off the supply and then the return line simultaneous with removing the jumper.