My son's 1996 Jeep Grand Cherokee / 4.0L Inline 6-cyl (180K miles) has a fuel delivery issue. There is no fuel pressure on the fuel rail while cranking (Schrader valve depressed to check). Also, the fuel gauge is not working. I know the gauge isn't working because I added 5-6 gals of gas hoping he'd run it dry. But no registration or movement of the gas needle at all. The truck was running fine and one morning last week would crank, but not start.
So, I disconnected the wiring harness at the gas tank and check for continuity through to the pump/sending unit. I found continuity across two of the four terminals. On the supply side of the harness I found no power with the ignition key turned to the run position. I don’t see any damage to the wiring from tank to fuse box.
I know that due to the miles on the truck I should suspect the pump unit, but I’m really not sure its getting any power. Could it be something simple I’ve overlooked? Fuses seem good, but I don’t know about the little black relays thingies in the fuse box – do they ever go bad? I’m looking to get out of this cheaply as I just sank $1500 into a new front suspension thanks to my boys accidental, rainy night, ditch run.
I qwould try a new fuel pump relay in the power distribution center. Pretty simple system. It completes the power circuit thru the ignition switch and the PCM. If this relay is not bad, then the only items left are the pump, PCM and ignition switch. I would think pump, but if you are not getting power to the pump, it may be something else. If the relay change doesnt fix the problem, supply power to the pump and eliminate that.