Crank no start, overheating coil?

I've had this problem 2 or 3 times. No spark.
If I poor water on the coil or open the hood and let it set a while it'll start right back up.
I'm assuming it's the coil.
Anybody ever heard of this before?
Should I replace the coil, relocate it or both?
'96 4.0

Thanks!

Crankshaft position Sensor.

Replace?

Probably the CPS.
If the coil is overheating it will nearly blister your finger, give it the touch test.
In most coils there is between 1 and 3 ohms of resistance in the 12 volt side of the coil. The Renix is 1 ohm, don't really know what the spec is for the 96 coil. On the high voltage side (Renix) it is 7-11 K depending on the temperature.
You also have to test for input voltage (key on and during start) backpinning the coil input. to make sure it isn't the wiring, PCM or the ASD relay causing grief.

Euclid said:

I've had this problem 2 or 3 times. No spark.
If I poor water on the coil or open the hood and let it set a while it'll start right back up.
I'm assuming it's the coil.
Anybody ever heard of this before?
Should I replace the coil, relocate it or both?
'96 4.0

Thanks!

Click to expand...

Haven't heard of jeeps having this problem. Really OT but, the pontiac 326 V-8 had a factory issue with coil overheating on the intake manifold becuase the coil was mounted with 1 terminal high, and one low. They just boil to death. Anyway, back to the topic. They don't get that much heat off the block, so I wouldn't relocate it.

It may be that the component suffering from "thermal heat failure" is cooling down at about the same time you pour the water on the coil. Not saying that it couldn't be a coil problem but I would be highly suspect of the crankshaft position sensor first as IMHO, that is the #1 most common sensor failure on the XJ.

Checking the CPS with a meter may or not be of value to you though if it is a thermal fail but you could try it. I think the spec is 200 ohms plus or minus 75. But again, if it checks out on resistance, that doesn't mean it's good. They can heat up and crap out too. I've seen it with the CPS. If your CPS is original on your 96, you may just want to replace it. I'm not a big fan of throwing parts at a problem but with thermal failures, sometimes you have to and if your CPS is original, putting in a new one isn't exactly wasting your money as it will go eventually.....My 2 cents!

The passenger side of the motor is generally much hotter than the driver's side. Is this normal? Perhaps there's a blockage in one of the internal coolant passages causing that particular area to get very hot?

If there was blockage internally, it would show up on your coolant temp gauge in your dash. I really don't think this is your problem.

You have a component that is failing when hot. Replace the coil first if you want as you seem to be suspect of that but my money would be on the CPS.

Previous owner told me that it was the coil although I was suspect. I will replace the CPS first, as it seems to be a common failure.

Any decent CPS write-ups? Just get a bunch of extensions? I assume normal parts store parts will work just fine?

Thanks!

Baller, thanks boss

MiNi Beast said:

http://members.cox.net/wilsond/Fixes/diagnostics.html#CPSdetails

Click to expand...

That link says it's for a '93 ZJ. Don't know if it's the same or not.

Here's a good write-up:
http://www.floridajeepers.net/viewtopic.php?t=20947&start=0&postdays=0&postorder=asc&highlight=&sid=ac8897d8c700a6214923f18bd75bc671

I think 5-90 has a write-up also but don't have the link handy.

Southwest Chuck said:

That link says it's for a '93 ZJ. Don't know if it's the same or not.

Here's a good write-up:
http://www.floridajeepers.net/viewtopic.php?t=20947&start=0&postdays=0&postorder=asc&highlight=&sid=ac8897d8c700a6214923f18bd75bc671

I think 5-90 has a write-up also but don't have the link handy.

Click to expand...

4.0 same terminology is applied. All engine have same basic operation to run.