it reads 48 psi at idle. seems high. I have to poor man prime it which is what sparked the inquiry. it bleeds off to 8 psi within 5 minutes after shutting it off.

edit: 97 xj. 4.0

 

48 psi is not high. Spec is 49.2 psi +/- 5 psi.

Dropping to 8 psi within 5 minutes is out of spec however. It should hold to 30 psi for 5 minutes.

Looks like you have a leaky fuel injector or bad check valves in the fuel pump module.

Does the engine run rough when you first start it? Leaky fuel injector(s) will load up the intake manifold with raw fuel and cause a rich start up idle until it clears. If it does look like you are seeing this, you can pull the fuel rail (with injectors attached) back far enough so you can slip some bits of paper towl or clean rags in front of the injector nozzles, then do the prime thing. If and injector is leaking it will show on the paper towl(s).

If they don't leak, think about replacing the fuel pump module.

 

the injectors are fine. I was assuming it was the fuel pump assembly.