i did a fuel pressure test on my 97 f150 4.2 everything is within specs except when i remove the vacume line from the presure regulator the presure didnt increase like the book said it should does this tell me my regulator is bad?
It should be about 32 psi with vacuum and 40 or so without.
If it sin't changing and you have a contant 40psi, then I would suspect the regulator. Did any gas come out of the vacuum port on the regulator?
i changed my pressure regulator it fixed the stumble and the hard starts for 1 day now its doint it again sometimes it surges when i take off it acts like it is running out of fuel but it takes off about a secong later