Fuel Pressure Problems

[AutoSHO]

Hello Everyone. I bought a fuel pressure tester a few weeks ago. I checked my fuel pressure and found it to be much too high (50 psi idle, 60 psi no vacuum). Last night, I decided to try and diagnose it. Hooked up the fuel pressure gauge before starting, and it read 38 psi at idle, 44 no vacuum. WTF? I unhooked the return line, no changes. The difference between the two tests, or the only difference I can think of, is that it was warm last night, and not warmed up the first test.

The kicker? I went out this morning and checked it, and its back up to 50-60 psi after sitting cold overnight. I'm going to check it warm when I get home today.

Does this sound like a bad Fuel Pressure Regulator? Its the only thing I can think of that would cause this. It would also explain why it runs erratically at different times. i.e. Bad throttle response, holes in power as I open the throttle, runs different every time I get on it. I think the fuel pressure regulator is my suspect. How involved is changing it? Is it a simple matter of unscrewing it from the rail?

Thanks for all your help!!

 

[AutoSHO]

Update: Just as expected, when I checked it hot, it was down to 44 psi no vacuum and 38 psi idle.

FPR?

 

[rangerj]

AUTOSHO,

It could be a fuel pressure regulator, or it could be a blockage in the return line. Key on initial pump up pressure should be between 38 ro 48 psi. Running pressure should be between 30 to 36 psi.(give or take a couple of psi)Check the pressure specification for your model year. rangerj

 

[AutoSHO]

rangerj:
AUTOSHO,

It could be a fuel pressure regulator, or it could be a blockage in the return line. Key on initial pump up pressure should be between 38 ro 48 psi. Running pressure should be between 30 to 36 psi.(give or take a couple of psi)Check the pressure specification for your model year. rangerj

I don't think its a blockage in the return line, because it didn't affect pressure connected or disconnected.

The other oddity is that it is affected by heat. Thats just weird. I think the FPR is faulty, I was just wondering if anyone else had similar problems.

As far as I know (someone correct me if I'm wrong) it should be ~30 psi at idle and 38-42 without vacuum. Thanks for your help!