So far everything that has been suggested has been tried but nothing changes, still stumped.

 

I'll throw some darts at this one...

Try the wire connections at the block, which then goes to the starter. Make sure they are clean and well connected.... then also look at the connections at the right side of the fusebox in the engine compartment. There are two wires bolted together. Make sure there is no rust and a good connection.

When it doesn't start, do you have power at all? I had this problem at it was the connections on the block. They were caked over with oil and grease (engine fire waiting to happen).

HTH

 

All the connections to the block are grounds and they shouldn't have power. I think I checked everything already but I must have overlooked something. No doubt it is something stupid that I'm looking right at.

 

This is a crank, no start situation right?

Your previous reply is dismissive. Does that mean you haven't check the grounds? It takes a full path to complete a circuit!

Have you checked if the ASD fuse and relay are good?

 

When it doesn't start, do you have power at all? I had this problem at it was the connections on the block. They were caked over with oil and grease (engine fire waiting to happen).

HTH[/QUOTE]

This is what confused me in the previous post "do you have power at all? I had this problem and it was the connections on the block" . Connections directly to the block are grounds, and all the fuses and relays have been checked. This is a crank no start situation, the strange thing is that there is no apparent reason for when it starts or doesn't.

 

Sorry, I wasn't trying to confuse you. From my past experiences with many cars and boats in my life, I've had intermittent starting issues that seemed like something more complex and it turned out to be a bad ground.

 

No problem, I've had the ground problem with a Cherokee before so that was one of the first things I checked. I believe I found the problem, I got my fuel test gauge today and I'm only getting around 18 psi, the one time that it jumped up to around 40 psi it almost started. My running Cherokee jumps right up to almost 50. Must be fuel pump or regulator, that means dropping the tank. I know that I have had a previous problem with a Cherokee that appeared to be a spark problem that ended up being a fuel problem. I hope I'm right, I'll repost when I get it fixed. Thanks for the help.

 

I put the new fuel pump assembly in today and to my disgust it still wouldn't start, I did have the correct fuel pressure though. I still had the test gauge on so I purged the pressure and tried again, it started . Tried it again, nothing, purged the pressure it started. This system worked repeatedly every time I just couldn't figure out why. When it wouldn't start there was no spark, purge it again and there was spark and it started. When it wouldn't start after turning off the key the ASD relay would flutter until the key was turned all the way off it would stop. When it started and the power was cut the relay wouldn't do anything. Just for the heck of it I disconnected the wire to the first injector and tried to start it. It blew the fuse to the fuel pump, replaced the fuse plugged the injector back in and it started, it has started every time since then and runs perfect. If an injector was in somehow clogged or stuck could it cause a high or low voltage situation that would trigger the ASD relay? Very strange situation all I know is that it starts and runs fine. Any explanations?

 

Maaaybe... I'd get out a multimeter and find out what's going on with that injector and check its wiring.

 

Wow! This is Twilight Zone stuff.

The PCM goes nuts when the bus voltage drops to below 9 volts. 10.5 volts is the normal minimum to make the PCM work. Have you monitored the batterry bus voltage during this exercise?

It wouldn't hurt to remove the main cover off the Junction Block and look for corrosion in there. It may mean removing connector C4 (the big guy with the bolt) to see what it looks like.

 

I have checked and cleaned every connection I can find, I haven't checked the voltage but I have had a charger on it while I have been working on it and the battery stays up fine. The strangest thing is why it would not start until I purged the fuel pressure and not until, and it did that every time.