Hey I'm trying to figure out if my fuel pressure regulator is bad heres what the problem is. When I put my fuel pressure gage on the rail and turn the key to the on position and not starting it. for the 1.5 secs the pump runs to prime the pressure jumps up to 42. But when the car is running its at about 38 PSI and when I open the throttle a little it drops to 33 or 34 PSI that is kinda low isn't it? The fuel pump is only about 3 or 4 months old and I replaced the fuel filter shortly after doing the pump.

Also I want to check the fuel pump pressure to see if the pumps pressure is dropping that low. But the only schrader valve is on the rail. Where can I get an adapter for my fuel pressure gage that will screw in where the rubber line screws in to the hard line? Do they even exist?

 

I believe if you are having fpr issues like a bad diaphram, the fuel pressure will bleed off fairly quickly after the car has been turned off. Like in less than 30 minutes. Have you checked for this yet?

 

Yeah, it takes hours for it to bleed off though...

I was just messing around with it and I don't think this is a big deal but when the pump is priming the gage reads 46 PSI right when the pump turns off it jumps down to 40 PSI. and stays at 40 for hours.