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87 XJ engine just dies....help!

pressurerat

NAXJA Forum User
Location
Tennessee
I have an 87 XJ 4.0 auto. While driving, the engine has started to just cut off and die, just like a switch was turned off. Everything else electrical still works. At first when it died the engine would restart right away. The last time it happened took 30 minutes before it would start. This problem just started three days ago and never happened before at all. It has done it about 6 or 7 times now with no apparent reason. There is no spark when dead, but plenty of fuel. What are the main culprits I need to check?
 
pressurerat said:
I have an 87 XJ 4.0 auto. While driving, the engine has started to just cut off and die, just like a switch was turned off. Everything else electrical still works. At first when it died the engine would restart right away. The last time it happened took 30 minutes before it would start. This problem just started three days ago and never happened before at all. It has done it about 6 or 7 times now with no apparent reason. There is no spark when dead, but plenty of fuel. What are the main culprits I need to check?

Ignition switch, TPS sensor, loose wire or connector anywhere in the entire ignition circuit. Tough one to track down until it quites entirely, or unless you find an obvious burned/burning wire somewhere.
 
My '88 did the same thing for a few months after I got it. One day when it would not restart,stuck in traffic, I just started unplugging and reconnecting every plug under the hood. I don't know which plug fixed it, but when I got home I went through each plug, using contact cleaner, and needle nose pliers for squeezing down on the female contacts. Haven't had the problem since last summer. It's the easiest ( and cheapest) thing to do before you start testing for bad components, which you could mis-diagnose anyway if you have a bad connection somewhere.
 
Thanks for teh input. I'm about 400 miles away from home is the crappy thing! I'm heading back this morning and I guess I need to check a couple of things.....bad part is I can't check till I'm broke down! Oh well. at least I have an 'extra' hour of daylight for my trip. The Haynes manual and voltmeter are in hand............I'll post back if I figure something out.:repair:
 
Ok....I think i narrowed it down to the coil or the ICM. When I tap on the coil with a wrench, the Jeep will start running again. I made it all the way home doing this for 400 miles. It stopped 5 or 6 times, but I made it. My question is: what years will the icm interchange with? Is it a Renix only piece or what? I'm going to the U-pull it yard tomorrow to try and find one.
 
pressurerat said:
Ok....I think i narrowed it down to the coil or the ICM. When I tap on the coil with a wrench, the Jeep will start running again. I made it all the way home doing this for 400 miles. It stopped 5 or 6 times, but I made it. My question is: what years will the icm interchange with? Is it a Renix only piece or what? I'm going to the U-pull it yard tomorrow to try and find one.
Looks like the 86 -99 spark coil is the same. For the ICM check an online store like autozone for an 87, 92, and 97 year ICM to see if the part number changed!

It sounds more like a bad, loose connection than a bad part! Remove the coil from the ICM and clean and tighten the input connections (which are hidden under the coil) to the coil and see if that fixes the problem! Also clean and tighten the connector(s) to the ICM.
 
I found a ICM/coil at the boneyard for $6.50 plus tax, it fixed the problem. It turned out not to be the connection or the wire harness, I cleaned and checked it. Thanks for all the input!
 
It actually sounds like it had been a bad ground at the coil. Could have been a bad coil, but 99% more likely the ground. Putting a new one in 'freshened up' the contacts and teh body connection. Bad grounding is the worst problem in the pre-91 XJs I've found.

BTW, a CPS that goes bad or needs to be reconnected won't make it quit. The Renix will keep going and estimate things. It's only during start that it needs good signal. It may not run perfectly, but it won't quit.

-Skip
 
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