Ok i have a 94 cherokee with the 4.0 ho motor. Ive been chasing the lack of power for a week now. Just went to the auto parts store and checked the fuel pressure at the rail with t running. the pressure was at 30psi. From what Ive read that it should be at 49psi. I had them order a pump borge warner ( was smart i said NO to the airtex). Now im going to replace it tomorrow should I also replace the pressure regulator at the same time? I know its on the rail toward the front of the motor. Now if it is bad how can i tell. If i remove the vaccum line while its running and gas goes every where (BAD). But could it let fuel run right back to the tank without maintaining the pressure?

 

The fuel pressure spec for your 94 is 31 psi at idle. So 30 is within spec. 49 psi plus or minus 5 is the fuel pressure spec for the 4.0 for 96-01 XJs

What you should also do though as long as you have a gauge is to disconnect the vacuum line leading to the fuel pressure regulator and the pressure should jump to approximately 39 psi. Also you should verify that the vacuum line to the FPR is pulling good vacuum and is not wet with fuel; if it is you have a ruptured fuel pressure regulator and must replace it.

So I think you need to do a little more testing. Good luck and keep us updated!

 

Ok ive been messing jeep. Here is an update.
I replaced the coil ,the fuel pump/ pressure regulator and the master clutch cylinder. My lack of power is gone. Guess the pump wasn't putting out enough pressure to keep up. Time for testing tomorrow keeping my fingers crossed she passes. Still runs a little rich gong to buy new injectors I posted in another tread.

Thanks for the help TJ