My question is can a fuel pressure regulator get weak?

 

I was asked the same question. My truck has started being hard to start. As if its not getting enough fuel. Filter has been changed a few months back. It takes a few starts sometimes to crank. THe fuel pump makes sound when key is turned but it runs rough and dies the first few cranks. An old gentlemen said check your pressure it could be the regulator but he thought my truck was carberated also. mine is 1996 4.9L

 

Yes, the FPR can go bad.

 

I know they can go bad as in make the fuel pressure go way up and all, but can they get weak and not let the fuel pressure come up to where it needs to be and make the truck run a little lean?

 

I've never heard on one doing that. I'm not saying that it's not possible, but I've never heard of it.

 

I guess I'm thinking that maybe the FPR can't hold the pressure and is letting more fuel return than it should. I checked my fuel pressure and at idle it is 30 psi. When I rev it up, it only goes up to about 34 psi and it does that on both tanks. It goes up to 40 psi when I disconnect the vacuum line. I just find it hard to believe that both pumps are exactly the same and the only thing that I know that they have in common is the FPR. BTW I'm running a little lean at around 1500 RPM. Anything above that and it seems to clear up.

 

FP should be 39 at idle with the vacuum disconnected and plugged.

When I post here at F150 online, bear in mind that although I do have a 1995 F150 with a 5.0, most of my FI experience is with my 1992 5.0 Mustang.

 

Richard the fuel pressure is at 40 with it disconnected, it's at 30 at idle with it connected but it will only go up to about 34 when I rev it up and it doesn't start climbing until i'm at around 2k RPM. Thanks for the reply.

 

it could also be the overpressure valve inside the high pressurepump.

 

Those are normal numbers. It sounds like the regulator is good. Usually when a regulator goes bad it's because the diaphragm has ruptured. There would be gas in the vacuum line if that occurs. The engine would also run very rich. Black smoke when it runs, blackened tail pipe and spark plugs.

 

I am having the same exact symtoms in my 4.9l .... it started acting like this right after it ran outta gas ..