2000Jeeper

So I've been messing with my cherokee for a bit, standard 4.0 from 2000. It idles low and rough, and has around 5 to 10 inches of mercury manifold pressure. Every so often it jumps back up to 15 and runs much better, then if I kill it and start it again it happens again. It has 18 or 20 pounds of fuel pressure, and doesn't go up or down regardless of rpm. Can't seem to find a vacuum leak, I looked with propane but there is a possibility I looked over one. Where would any of you go from here? Any input would be great, thanks

rgr4475

The 00-01 have the 0331 cylinder head which is prone to cracking. I am not an expert in this area, but that seems to be some of the symptoms. Any loss of coolant too? Either way, may be something to keep in mind.

Turbo X_J

Fuel pressure should be 49 psi +/- 5, don't replace with a white box pump unless you really like changing them.
If a person is suffering a heart attack treating a paper cut shouldn't take priority.

tjwalker

Yup, your fuel pressure is WAY low. As Turbo X J mentions, spec. is 49 psi plus or minus 45 psi.

Replace your entire fuel pump assembly. Bosch is my first choice, Carter is my second choice. Do not use Airtex fuel pump assemblies for the XJ, search and you'll find out why.