got an 03 f150 that starts and idles fine but when i put er in gear it seems to misfire It will barely run when under load The truck was ran out of fuel a\nd has sat for 3 months I installed a new fuel filter no difference the fuel pressure is 30 at idle and 40 under load
Any ideas??

 

ncb, I moved your thread to this forum hoping you might get a better response. It's quite possible you don't have a fuel problem at all. There are several other things that can cause what you describe.

I think 30 psi is adequate at idle, but possibly 40 psi is too low above idle. I know a 2004 truck should be 30-45 psi at idle. Your fuel pump may have been damaged by running out of gas. I think that is a possibility.

- Jack

 

40 psi under load is within spec.

If you pull the vacuum hose off the FPR, the pressure should rise by about 5 psi. Also check to see if there's any evidence of fuel in the vacuum hose.

 

if it only does it under a load it may be electrical... coil pack or plugs would be my first guess... you shouldn't notice a miss with that fuel pressure...