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acilate 06-03-2013 11:34 PM

'91 XJ 4.0L dying randomly
...and the crank sensor has already been replaced - it didn't fix the problem.

It REALLY seems like the crankshaft sensor:

Randomly while driving, all power is lost from the engine, and the tach drops to 0, even if I'm on the freeway and I *KNOW* the engine is still turning. The other gauges seem normal/don't change.

The issue will fix itself within a couple seconds, often before I stop, and usually doesn't need to be started again.

Could it be wiring for the crank sensor? Is there a cam senor maybe?

My only other thought is it could be the computer.


acilate 06-04-2013 12:14 AM

Re: '91 XJ 4.0L dying randomly
This Jeep is a recent acquisition - my girlfriend has had it for a while, but is driving another car as her primary until we can get the XJ running well again.

I have some other concerns as well. She has been sitting unused for almost two years. I usually turn her on once a month and let her run for a half hour or so. Sometimes I go 2-3 months without a start due to bad memory :o

I'm concerned about condensation in the gas tank. I've added stabilizer to the gas.

What other items should I be concerned about? What should I check to make sure she is running the best she can?

The motor has 200,000 miles on it, and seems ok, (besides a "clanky" sound from the head) but I know its only a matter of time before things start dying.

4.whoa 06-17-2013 11:47 PM

Re: '91 XJ 4.0L dying randomly
condensation in the fuel as well as stale gas will make it run rough, but not cause the problem you're having. No a '91 does not have a cam sensor. is there any certain thing that brings this on ,like hitting a bump or whatever ?

acilate 06-18-2013 12:38 AM

Re: '91 XJ 4.0L dying randomly
Not to my knowledge. It always happens while moving, but beyond that, it seems fairly random.

bruce van wyk 06-18-2013 06:38 AM

Hi I had the same problem with my jeep they replaced just about every part in the car and it ended up being the lambda sensor

acilate 06-18-2013 07:58 PM

Re: '91 XJ 4.0L dying randomly
Hi Bruce!

Thanks for the info, I'll check it out. Also, welcome to Jeep Garage!

bruce van wyk 06-19-2013 02:38 AM

Re: '91 XJ 4.0L dying randomly

Originally Posted by acilate (Post 844279)
Hi Bruce!

Thanks for the info, I'll check it out. Also, welcome to Jeep Garage!

thanks hope that it comes right

Frango100 06-21-2013 09:28 AM

Re: '91 XJ 4.0L dying randomly
Don' t know the XJ, but it seems that the 4.0 gives problems alike on the WJ. Some guys found a cable bundle at the aft side of the head, resting against a bolt. Over time a wire will shave through and will be resting against ground. Alsoproblems arrose due to too long bolts securing the PCM, causing a short. Don't remember exact which bolts its related to, but some googling probably can help you further.

Frango100 06-22-2013 05:14 PM

Re: '91 XJ 4.0L dying randomly
Here a link to the site mentioning the problem with the PCM bolts: Jeep Grand Cherokee stalling fixed! - CNET Car Tech Forums

acilate 06-28-2013 01:25 AM

Re: '91 XJ 4.0L dying randomly
Thanks! I'll check it out.

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