I have a 1992 4.0 XJ that would crank indefinitely but not turn over at 7AM this morning. I did not hear the fuel pump turn on at all when turning the key to the on position, and had no pressure at the fuel rail. (The check valve, I think, has been bad for a while so it generally takes some time to start after it sits overnight.) I've never not heard the pump come on before though.

After researching replacement fuel pumps and doing some reading on here I went to check a few more things at noon... and the fuel pump kicked on when I turned the key and it started and ran fine. Since it runs okay now I'm pretty sure that the fuel lines, injectors, etc. are all okay and nothing is physically pinched or damaged.

I'm thinking that it was maybe a condensation issue causing a short in the fuel relay somewhere? It just cooled off here a few days ago so there was a lot of dew on everything this morning. Anyone have any experience with something like this? What fuel system components do I need to check if this issue happens again? I'm relatively new to working on cars so am still learning where everything is. Thanks for any help!

 

Try swapping the pump relay with the horn relay. If it cures it, get a new relay.

 

Thanks, good suggestion. For now it seems to work fine; I'll have to wait until it's a problem again before I can troubleshoot it that way. In the meantime I'll try to look at the rest of the connections in the circuit.

 

Look at the supply wire to the relay it might be broken or bad(as is in an intermittent connection letting it run) . If it was just the relay it would start while cranking,then quit when you let off the key,from cranking