I posted back a few months and have just been to busy to work on the jeep till this week. I have a 94 4.0 manual trans cherokee that has no spark, starter just goes and goes but no start. I have replaced plug wires,cap,rotor,coil,module up in bottom of dist,battery cables, battery and crank shaft sensor. Was told to check the O2 sensor and it is good. Still have same issue no spark and sometimes it will crank run anywere from few minutes to few hours. I'm still lost.

 

There is only a couple of items left,cam position sensor and pcm.

 

Is the Cam position sensor in the bottom of dist--if so I change that. I have looked around local salvage yards and have had no luck finding the PCM anyclue where i can get one.

 

Found a computer installed it cranked and a minute later dead.

 

On your year there is the crank position sensor and a cam position sensor,did you change both?the crank position sensor on the bellhousing is the one that goes out most.
Not sure if that is your problem though if it ran with a used pcm,then died,I assume it will not run at all now?

 

I changed the one in the bellhousing and its a flip of the coin it may start it maynot. It didnt just after it shutoff i will go try it again.

 

No crank this afternoon I'm gonna give it a try tomarrow morning. Any clue where I can get a wiring diagram

 

So I gave it a try again today and it cranked up and ran for 10 minutes before it shutoff. It kinda missed a few times once just after it cranked then just before it shuoff. Any idea?

 

I guess that you checked for spark? Did you also check fuel pressure?

 

Have not checked fuel pressure but it has no spark so I just figured it was an ignition problem. Will it lose spark with no fuel pressure?

 

How about the coil. Have you checked the coil health out? The CPS does control spark timing but, you still have to have a good coil to get a good constant spark. You can read it out with a multi-meter or take it to Autozone. They will check it on their bench for free. $50 bones to replace it it, if it is bad.

 

Replaced it

 

One thing that will help to know is,next time you get it to run and it dies,check your fuel pressure with a guage and check for spark,it is possible you do not have either one or it may have one or the other,see if you can here your fuel pump when you turn the key on,gather as much info as possible and with evryones help we will find the issue,sometimes it can be a pain.
When you say no spark are you actually pulling a plug and checking it?

 

Pulling plug wire and putting a screwdriver in it and watch for spark to motor. I hear the fuel pump when I turned the key

 

I know you have replaced the cps,and pcm,but it points to one or the other,is it possible the cps is getting hot or the wiring for it?