I have a 1996 Cherokee 4.0 that has a long cranking time when it sits for more than 5 minutes. It helps if I prime the pump a couple times before turning the engine over. Plus I started it up,let it sit for 15 minutes and then I held the shrader valve open and there was no pressure in the line,so I know it's definitely draining back.

When I got this back in May it didn't have any trouble starting up,but after a while it began doing this. I'm not really concerned because it's just really a hassle more than a safety or performance issue. My "ex-mechanic" told me it's the fuel pump and sense it was the original pump and I was planning on road tripping with it,I figured I'd be replacing it either way. I went with a remanufactured Jeep OEM pump (don't make OEM new pumps) because reviews on aftermarket pumps were terrible. I changed the filter and sock while I was in there,and doing this made no difference.

My best guess is it's the check valve. I read somewhere that on this particular year,the check valve is in the pressure regulator and that's in the tank on the assembly. I also read you can't get a new pressure regulator for this year. What I want to know is,if I bought a whole new fuel pump and sending unit assembly,would I be getting a new pressure regulator that would fix this problem?

 

Don't just assume it's the fuel pump or check valve. If your injectors are leaky the same issue will be present. If they're original then they are probably due for replacement anyway.