Intermittant no start

[maigesheng]

Hi folks. Long time no post.

I have a 1990 Jeep Cherokee Limited 4.0 tilt-wheel 4x4.

Every morning when I get ready to go to work, it starts fine. When I get to work, I will turn it off and try to start it again. ...Starts better than before cause it is warmed up.

But, if I leave it off for 15 minutes or so, it will not start. It will then tend to not start again for between 10 minutes to half hour to 4 hours. The problem has been progressively worse.

However, today, I went in the store for 15 minutes and came out and it started right up. We went to another store and shopped for an hour and when we came out again, it didnt start again for a total of about 3 hours.

The vehicle cranks but will not fire.

We have changed the starter. (fail. Nothing wrong with the old starter.)

We have replaced the ignition switch. Fail. Still wouldn't start. We have tried to feel if any of the many wires are loose. Nothing seems to be working.

My buddy that is helping me look into it is a knowledgeable mechanic and is embarrassed to say that he is finally stumped. He suggests getting a chilton but, my feeling is that that book will not be detailed enough.

I read something about a CPS grommet?

Ok. Can you tell I am shooting aimlessly/

Anyone else have any ideas?

Thanks in advance.

 

[SteelHeadz]

From the prior threads posted similar to the symptom, if i remember correctly, it was mentioned to check the connector on the CKP sensor for corrosion or loose connection.

 

[KevinF]

The Crankshaft Position Sensor (CPS) is NOTORIOUS for causing intermittent starting problems, and I'm about 90% sure it's the cause of your problem, based on what you describe.

Less than $100 later (get the Mopar one, rather than the AutoZone/aftermarket ones) and a little labor, you should be up and starting properly once again.

Kevin

 

[jeepcrazy5722]

I had the same problem with a 1988 jeep, I replaced the ingnition coil, TDC sensor, relays, plugs and wires, and distributer. It ended up being the ground wire on the block was dirty, cleaned it up and no more problem. Hope that helps

 

[FloridaCherokee1988]

Just replaced the crank sensor in my 88 XJ, had the same symptoms. It's only a $30 part and if you replace it and it doesn't fix the problem you can always return it and reinstall your old one.