when i had my oem fuel pressure regulator with the fuel pressure gauge the pressure stays constant same for a long time. just key on.
i put on an aem afp reg. and now key on the pressure stays on like 40 psi then slowly drops down for a couple of seconds.
i thought my injectors were leaking but put a hose clamp on the end of the fpr it stays constant no drop. but now i dont know if my aem afp reg is bad and its new?
or what else is the prob. i run it and no pressure drop. when engine is running.

 

Is the afpr bad?

 

More information needed, were you running 40psi on stock FPR or were you at a lower value, but stable with no drop. All you specified was it stays constant.

If it was lower pressure before, and now youre trying to hold 40 and you cant hold 40. What is your fuel pump and what is it rated for in lph? How old is it?

Do you have any other potential leaks? Fuel Filter, Fuel lines, Fuel rail, etc.

It could always be the aem fpr, 5% or more of manufactured products across the board are sold defective. It happens.

 

Ok, it was like around 35- 37psi ish with only key on with the oem one. No drop. I waited like couple hours and it stills stay contant pressure. My fuel pump is oem and 202,000+ miles on it.

When i installed my aem afpr it was same as stock pressures. Tested it key on. It dropped slowly the gauge. Idk whats wrong. Same psi like stock but drops psi on the gauge.

When i run it engine on the pressure stays constant. Then i adjusted it to 41 psi.
Shut off key on jumps to 41 psi then drops again.

 

If the place you bought the FPR from has a good return policy id probably swap it just to see. Tell them it fails to hold fuel pressure, see if they will swap it.

 

Why do you want adjustable one anyway, any mods? Are you running an aftermarket fuel rail too?

I would do the standard fuel pressure test, I assume you have a gauge hooked up the fuel filter?

How does the car run, why are you checking fuel pressure?