lost spark
 

(94 jeep 4.0 manual trans) My jeep was driving fine then it just shut off, if I turn the key the starter just goes and goes but no start. I have replaced plug wires,cap,rotor,pick up in bottum of dist,battery cables, battery and crank shaft sensor. Still the same thing sometimes it will crank run anywhere for 5min to 1 hour (one time it ran all day) then dies and turn the key and the starter will just turn the motor and turn the motor.Any ideas

From everything you have replace the two things that will cause this are camshaft position sensor,different than cps,and the coil. These items when that get worn and hot will build up resistance to the point they will not work right or at all,I would test them and see if they could be the issue.

I forgot to to say I changed the coil and also camshaft sensor

it is in the dist,also to test it you will need a manual,the procedure is more than a little involved but is easy providing you have the procedure.

Changed the coil and also camshaft sensor. How bout the computer?

You have a camshaft position sensor and crankshaft position sensor,did you change both?one is on the bellhousing and the other in the dist,either will cause this issue,cps being the most common.

yea changed both

Computer can be a problem,but you would want to make sure the part numbers are the same. also you are 100% sure it is spark and not a fuel problem or posibbly exhaust,I have also seen 02 sensors cause this issue, But I would be checking everything before you spend alot of money on just replacing things.

pulled fuel line off before the rail and put it in a bottle , turned the key and it sent fuel in. Where is the o2 sensor and how can i check it

Yours is behind the cat,assuming it is a 94. When I have seen it it is on 96 and above cherokees that have two,you check them running and back probe them and check for a voltage of approx .0 to 1.0.
You should check your fuel pressure with a guage to make sure you have good pressure.
But you said you do not have spark,I am just asking the other questions to make sure.

I'm gonna check it out -- will let you know what happens thanks for the help.