Hey everyone, brand new to the site because I need some help. Here's the rundown:
I have a 1993 Cherokee 2door sport with the 4.0 high output, manual trans. It's only lifted 3" with 31" rubber so nothing crazy.
Last weekend out of nowhere it wouldn't start. After about 30 minutes of trying it started and I got it home. The next day I drove it to go duck hunting and it was fine all day. But that night it wouldn't start again, and didn't start the next morning. I eliminated all possible problems at that point besides the fuel pump and filter. I replaced those early this last week and it wouldn't start at night or in the morning, but would fire right up in the afternoon. It ran all day yesterday and then stopped last night. Any ideas as to what could be the issue? Here is the list of all the parts I have replaced the last week:
Fuel pump
Fuel filter
Fuel pump relay
Auto shutdown relay
Ballast resistor
Crankshaft position sensor (CPS)

The last thing I can think of is a new ECU, since there is no power getting to the pump or the CPS. Thanks for any feedback!

 

When the jeep won't start, what is preventing it from running? Are the injectors firing? Is it getting spark? Work from one side (fuel) to the other (spark) or vice-versa, doesn't matter. It'll be easier to diag if we know what we're dealing with.

 

The fuel pump is not turning on when the key is turned to the on position or when trying to start. Therefore there is no fuel pressure at the fuel rail. From what I can tell there is no spark either, I have never tested for spark before this but I can't see any arcs.

 

Definitely important to verify no spark. I would check your wiring and connections first. If I were to take any guesses right now.... I'd say ecu.

 

I have check all of the wires I know to check, I used a nail and screwdriver to try to get an arc the the block but nothing. I'm guessing ECU as well, just wanted additional opinions before I spend $200! Thanks for your replies.

 

Just so you know, you can pull a spark plug out and ground it to the block or any other good solid ground and watch for an arc to jump on the between the ground and electrode on the spark plug. Autozone also sells a spark checker tool thingy for like 9 bucks. It's easier to use IMO since it has a clamp to hold it to your ground.

 

If it doesn't do anything at all when the key is turned it could be your neutral safety switch (NSS) mine went bad and wouldn't do a thing when I turned the key. Once I put in the new NSS it fired right up. Cheap too only about $40