does fuel pressure hold with the engine off??

[IMPORTSMOKER]

I am curious if ; when i turn the key on, the fuel pressure goes up to 41psi...via aftermarket gauge...with the engine still off and key on...the pressure will slowly drop..like its pullsating down until about 25 psi where it sits...but when i turn the engine on...it holds pressure, of course, and then after running it...shut it down and it will hold the pressure now....do i have a fuel leak or is this the way the electric fuel pumps work???

 

[blk92stangg]

From what I understand the regulator, as well as the fuel pump has something to do with holding pressure at the rails. When I changed my regulator, the fp no longer holds at ANY pressure, with the engine off. So I need to crank the engine a little longer on start up, or cycle the key on and off a couple of times to get the pressure up...hopefully when I change the pump the pressure will hold, at least over night.

 

[HISSIN50]

as said, the FRP or the check valve in the tank can be responsible for bleed off. seems to happen on many cars with no adverse affects (if the pump and system hold proper pressure once running).

some FPR's seem to be more prone to bleeding off almost instantly after the car is shut off.

one can CAREFULLY crimp the return line to determine if the FP check valve or the FPR is at fault.

good luck.