Is there anything other then a wiring issue that will prohibit the fuel pump from priming when the key is turned?
I've been having some issue's with my 4.0L 98 Grand Cherokee. At first I just had trouble starting it. Would turn over fine but not start. I could hear the pump kicking on like it should. Changed the coil, crank position sensor, cap, rotor, wires, and plugs. Everything finally seemed back to normal and I drove the Jeep for a week. I filled the tank up one day on the way home and made it a couple blocks when the engine just died and would not start back up. Turned over fine, but this time I couldn't hear the fuel pump coming on. Went back a couple hours later and it started right up.
Haven't driven it much since, it did die again on my wife just backing out of the parking lot-same deal no pump. I can go out and start it right now but something somewhere is definately going out. I assumed the pump being a electric motor would either come on or not-can they act up intermittently (other then a wiring issue)?
On a side note, the fuel gauge cuts out a lot-has since the day we bought it 6 years ago. Just wondering if it might be a wiring issue since the pump and sending unit are there together.
You can swap the fuel pump relay out with another relay that doesn't work as hard, like the intermittent wiper or horn. Or you can splurge and go to NAPA and get a new one and stick it on to see if it helps. They are around 15 bucks.
Also, when it will not prime, go back to the bottom of the fuel tank and give it a good whack on the flat part to see if the pump kicks in. If it does, there's your sign.