Hi Guys !

I'm a long time Jag owner: drove my old 88 XJ-6 for 275K and I still own it. Here's my problem: I began getting a check engine light on my 98 XJ-8 about a month ago that turned out to be P0171 and P0174. I purchased a mid priced scanner and began to learn to to use the diagnostics, with a great deal of help from reading previous posts on this users group. I've owned this car three years now and this is my only check engine and restricted performance issue. I checked the usual culprits: vacuum leaks, MAF sensor, verified partial load breather was clear, replaced fuel filter, and pulled all spark plugs which all positively verified a lean burn. A couple days ago, I borrowed a fuel pressure gage at Autozone and I am only getting 24psi on the fuel rail. Here's what I concluded: at 24psi, I am getting enough fuel to run the car under most conditions with the car's computer enrichening as much as it is able to keep it running smooth. If I perform a hard reset of the computer, the scanner shows all fuel trims at zero and the car runs really rough until the fuel trims begin to make the mixture more rich. I am still not sure if I have a fuel pump issue or a fuel regulator issue. I tapped the regulator with a plastc hammer just to see if there was someting stuck that would bypass too much fuel back to the tank...got no change. Next I plan to check voltage on the fuel pump. I was wondering if I should remove the fuel regulator and plug the outlet long enough to see if I get a substantial increase in pressure on the fuel rail before changing out the fuel pump and filter. Any ideas would be appreciated.