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Unread 01-02-2015, 08:02 PM   #1
daltonfarr69
Registered User
1987 YJ Wrangler 
 
Join Date: Jan 2015
Location: wauchula, fl
Posts: 2
4.2 engine trouble

Before i start i researched a lot before posting this but can't seem to find an exact match to my problem.

The jeep is a 1987 4.2 with the stock carter carb.

Recently it has been having trouble idling and i know that a bad vacuum line is to blame. But the last few times i have driven the jeep the engine will shut off while Im driving down the road in gear. This happens not at idle but in higher RPMs. When this happens it is as if somebody kills the ignition switch and the engine looses spark. after the engine dies ill try to restart it and the engine will fire up for a split second and die immediately (this happens dozens of times till it finally stays running). After several failed attempts the engine will catch and stay running.


Im pretty sure this is not a fuel pump problem because i can smell the unburnt fuel passing through the engine. I was looking at attempting the Nutter bypass but before i attempted i was going to pick yalls brains first.


Thanks for yalls help

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Unread 01-02-2015, 09:10 PM   #2
Mike Romain
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1986 CJ7 
 
Join Date: Nov 2007
Location: Off the Grid in Chester Grant, Nova Scotia, Canada
Posts: 14,432
A bad ICM can act like that.
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89 YJ Renegade. BBD Carbed 4.0 HO. Locked front and rear with 33x9.5 BFG AT's
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Unread 01-02-2015, 09:18 PM   #3
rshbutch
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1990 YJ Wrangler 
 
Join Date: Mar 2009
Location: fresno, ca.
Posts: 97
Had same problem. Replace icm
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Unread 01-02-2015, 09:24 PM   #4
dancytron
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1990 YJ Wrangler 
 
Join Date: Jun 2008
Location: st. louis
Posts: 1,405
ICM (ignition control module) is what was wrong with mine when it did that. Hard to test it because it is intermittent. You got to wait until it fails to test it.

Some people replace it with a chevy type from hei distributor.
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Unread 01-02-2015, 10:10 PM   #5
daltonfarr69
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1987 YJ Wrangler 
 
Join Date: Jan 2015
Location: wauchula, fl
Posts: 2
cool thanks guys, i think ill go ahead and order a replacement.


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Unread 01-02-2015, 10:12 PM   #6
sardog211
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1989 YJ Wrangler 
 
Join Date: Jun 2012
Location: Gulf Coast, Alabma
Posts: 130
CRT HEI and never use that darn icm ever again
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Unread 01-03-2015, 04:28 AM   #7
roadyrob
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1987 YJ Wrangler 
 
Join Date: Apr 2007
Location: west palm beach fl
Posts: 1,837
it could be a bad icm but when mine did that it was the ignition switch. X2 on the CRT HEI, save the money you would spend on a ICM and get the HEI distributor instead.
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