I just tested the fuel pressure on my 2002 GT (140K mile original engine) and need some help figuring out what the results mean.

First - I was getting the Service Engine Soon light and the 0171 & 0174 engine codes meaning running lean on both banks, but before I tested the fuel pressure I disconnected the battery for 5 minutes (just cleaned the MAF which was probably oily from an overoiled K&N filter) and I am no longer showing the Service Engine Soon light...so I guess that's good. anyhoo, the test results:


when I hooked up my acutron pressure gauge to the valve on the fuel rail and turned the key to the on position it showed 12psi, turned the key back off and on again and it was at 34psi, turned it back off and on a 3rd time and it showed 40psi, where it remained no matter how many times I turned the key back then returned it to the on position. I relieved the pressure and repeated with the same results.

with the engine running it was showing a steady 34psi, moving maybe 1 or 2 psi as I revved the engine.

any thoughts??

 

well sounds like your code problem was the MAF...as far as pressure thats just your fuel pump building up pressure in your line each time...your idle pressure seems alright but it looks like it took awhile to build up to that..