89 YJ...which coil and which Ignition Control Module? - Jeep Wrangler Forum

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Old 10-03-2011, 12:44 PM
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89 YJ...which coil and which Ignition Control Module?

Just as the title says... I have an 89 YJ with the 4.2L six. It is having the intermittent problem of running fine and then just dying. Won't start for about 10 minutes and then it fires back up and runs fine... for about a mile.

Read a bit on here and see it's a pretty common problem. Looking to replace the coil and ignition modules. Jeep has been nuttered and has a 2150 carb on it.

What I need is some part numbers or stores where you bought them. Are they direct replacements? Will they just plug in where the old one was?

Normally I would do this research myself and figure it all out but right now I just don't have the time and you guys seem to have done most if this stuff already.

A little help would be most appreciated.

Thanks in advance.

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Old 10-03-2011, 03:30 PM   #2
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just out of curiosity, does it die when accelerating, stopping or turning specifically?

The only reason I ask is because I've seen the same symptoms with having a little water in the gas. It drives great until you turn and water splashes over to the fuel pump and fouls the spark plugs. Ten minutes later the plugs are dry and your good to try it again.

Just something to check... A key way to tell if this is happening is that it would hardly ever do it on a full tank of gas because the chances of water hitting the pump are slim. The lower the guage goes, the more likely it is that it would suck water.

I would also save some money and have each part tested at an auto parts store before replacing them. Next thing you know... you'll replace the coil, replace the wires, replace the plugs, replace the ignition and low and behold it will still happen because its the computer or water in the gas, etc...

You have two choices. Throw money at it until its fixed. Or take the time to troubleshoot (or find a good experienced tech) to troubleshoot for you then you only have to repair what is failing instead of replacing part after part after part.

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Old 10-03-2011, 03:49 PM
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This was driving straight down the freeway. Just cruising along and it would spit and sputter and die. I would coast to the side of the road and try to crank it. It turned over but got no spark. I know it's getting fuel because when i was coasting to the side of the road I tried to start it by letting out the clutch and it would backfire, telling me raw fuel was making it through the motor. And I can see good strong jets of fuel in the carb when I push the accelerator. And it's full of gas.
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Old 10-03-2011, 09:48 PM   #4
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Can your local parts house look it up and sell you ICM that i sounds like you need? Sounds like what the old Fords did back in the 70s and 80s.
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Old 10-04-2011, 03:31 PM   #5
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Im afraid i dont have part numbers available for you, but this is what i did and recommend:

-i found a TFI ignition coil and mounting bracket in a junkyard. The swap wasnt exactly 'plug n play' but it was pretty close. Just remove the horsshow connector for the old ignition coil and attach posite to positive and negative to negative. Switching to the TFI col will require a new coil wir as the connection is different from that of the canister style coil.

-on the same junk yard trip i found the wiring harness connectors for the old ford duraspark ICM out of a late 70s ford truck. The ICM in our jeeps and the one in those ford are identical aside from the connections and price. I switched out the plugs on my wiring harness for these and bought an autozone ICM for that year ford truck with a lifetime warranty. When you mount the ICM move it somewhere where it can get more air flow.w i mounted mine on the inside drivers fenderwell.

-do a little research when you have time on adding aux grounds to the ignition system of these jeeps. It will vastly increase the lifespan of your Icm.
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Old 10-04-2011, 04:02 PM   #6
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Just go to basically any parts store and give them the year & engine and they can easily look them up and most likely have both parts in stock. They are both plug & play. Common parts.
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Old 10-04-2011, 04:29 PM   #7
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Don't replace wih stock parts... The ignition is a choke point in these old Jeeps. Even after the Nutter bypass the small distributor cannot handle a hotter coil efficiently. Look into getting an HEI dist, its a simple swap with only 2 wires required to install. In my experience, the HEI works much better than the TFI Team Rush upgrade, and is alot simpler.
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Old 10-05-2011, 07:16 AM
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Thanks folks. All good info. I am headed out of town this weekend but will get on this next week. Jeep still sits at work. I found some info on the TFI coil swap and have been curious about it. Might look into that.

Again, thanks for the info.

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Old 10-22-2011, 01:39 PM
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Thought I might bring this back up. Finally got the Jeep home. It would fire up at work and run about two minutes and then it was like I turned the key off... it would just die.

Got it home and off the trailer and it won't act up on me again. I have taken some short trips not too far from home in it with no issues. I have done nothing to it at all. I refuse to drive it any distance because the issue hasn't been fixed yet. I let it run in the driveway this morning for about an hour... no issues whatsoever.

You have to love intermittent problems. Thinking about a new ICM and the Team Rush upgrade just to upgrade the ignition system.

Any ideas?

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Old 12-10-2013, 07:09 AM   #10
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Perhaps this post is a little on the late side, but I am having very similar problems on mine. I replaced the coil, wires, distributor with the TFI system and have had no luck. Did you replace the ICM? If so, how is it? I've been told this problem could also be the CPS or the MCU.

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