1988 Jeep Cherokee, In-Line Six, Automatic Transmission, 4X4. When its running, it runs great. Park, sits for a short while, try to start it. It turns over just fine, but it won't catch, won't even cough. On two occasions towed it to a shop and it starts just fine. On one other occasion it sat overnight and started. Any ideas?

 

Next time it happens you need to see if you have a good blue spark and the right fuel pressure. your yr should have 39psi at the fuel rail.

 

yep, checking for fuel pressure and spark are the first things to look at

 

I would test the CPS first. See post 7 in my tips.

I would also perform posts 1 through 5 in my tips as a matter of course. Maybe just do that first.......

 

Fuel pressure is good. When it won't catch, no spark. But then, there the arc was, and it started. Did the Renix Treatment, cleaning all the points Cruiser 54 suggests in his pink posts. The crankshaft sensor has been replaced. Still intermittent issues. What would you suggest next?

 

Where did you get the new CPS from? It is very common for the aftermarket ones to be bad right out of the box, If they do work they are known to have a very short life span. If it is an aftermarket one I would suggest to return it and get an OEM one, Also check to make sure that your coil is working properly.

 

yep, there are tons of posts about CPS's being bad right out of the box on the cheap units

 

true facts been there lol !!!

 

Does the OEM crank have to come from Chrysler/Jeep dealership?

 

Pretty much.

I like the PC307s from RockAuto.

They ARE OEM and they advance the ignition timing a bit...

I still drill the mounting holes per Post7 in my Tips....