Hey guys, I tried a search but couldn't find any threads dealing with this exact problem.

My nephew called and said his Jeep (90 XJ 4.0L) was shutting off at highway speeds. It happened 3 times during an 80 mile drive. When it shuts off the lights, radio, gauges, etc, all still work fine and when he turns the key it will start right up and runs fine. Over the phone I had him check out some basics, battery terms, ignition wires, sensor plugs, etc. but it all seemed good.

I'm going to be taking a look at it when he gets back on Sunday and was wondering if anyone has ever had this same problem before or could give me some ideas of things to look for.

Thanks
Dennis

 

Does it have cruise control?

 

ya i have herd if the cruise control is shorting out it will shut down the motor. only once tho. good area to look at

 

could be the cruise control or even the computer itself. Does it have an alarm in it? if so it could be that also.

 

Thanks for the replys!

It does have cruise control, but it has never worked.

It has never had any aftermarket alarm system installed. The Jeep is pretty much all stock.

He drove it from Texas to CA. (pretty much non stop), a couple of months ago and had no problems at all, and he was even towing a trailer. This is a brand new problem that just started.

Dennis

 

A flaky "crankshaft position sensor" could do this.

If the computer loses the input signal from this sensor, you will have no spark and you will have no fuel going TO the fuel injectors.

The crank sensor is a VERY common failure on the Jeep 4.0 engine.

 

I got a chance to look it over today. I pulled the coil wire off and the coil terminal was very rusty looking, and the wire end did not snap onto the coil terminal tightly either. So I made up a new coil wire and cleaned the rust off of the contact terminal on the coil. We'll see what happens. I hope it was that simple! If it still dies I guess I'll try the crank sensor (as jtwalker suggested) since I have a new one sitting on the shelf.

Thanks again for the help guys!

Dennis

 

This is way outside the box, but something to think about.

Read about a car that would quit intermittently.
Turned out after much troubleshooting and tows home,
Someone stuffed a plastic bag into the tank and it would find its way to the fuel pickup.
After coming home on the hook the bag would float off until the next event.

Might not have anything to do with this post,
but never overlook the fuel pickup....

 

check wiring for the crank position sensor it very possible wires thru the years have become dry rotted and could have a bare spot grounding out to engine common issue

 

Just a thought! Did you take a good look at your Cat. If so equipped!

 

I don't think that is the case with this one because as I said, it will start right up after it shuts off while you are still costeing down the highway. But thank for the input!


I'll check that if it is still having the problem, thanks!

I think the Cat is working properly because the Jeep was recently smogged, and it passed with no problem. They are pretty stricted about the proper operation of the emissions related parts here in CA.

Thanks for the input though!

Dennis