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Old 07-29-2012, 05:19 PM   #1
megax05's Avatar
Join Date: Jun 2012
Posts: 124
4.0l HO yj not starting.

recently i was working on my 91 YJ with the 4.0L engine there was a problem in the starter and i replaced the starter cluch drive and stop ring then put things together and tested and then engine wont start i did double checked everything but nothing wrong there engine is getting gas and also getting spark however the problem still there I replaced my crank position sensor and car didnt drive for more than 5miles on that sensor.
any sugestions?

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Old 07-29-2012, 05:42 PM   #2
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Join Date: Mar 2012
Location: Ridgway, Pa.
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Unless the motor was switched, a 91 didnt come with an HO motor in it.

Did you unhook the battery cable before you worked on the starter? 1 wrongly placed spark i.e. positive cable touching a ground and arcing, will destroy the brain of the ignition....ICM.

Did you check the spark? is it a weak yellow at a plug or bright blue? The ICM will allow the system to cycle with a weak spark, but it wont fire. Most you will get is it will sound like it wants to start, but dies as soon as you let off the key.

You have fuel, it rolls over, and you have spark, it has to run. Those are the basics.

The ICM is an aluminum looking box that is mounted to the inside of the driver's side inner fender, down in behind the windshield washer bottle. Unfortunately, i dont think there is any way of testing it, other than to try one out of a friends jeep and see if yours starts...they are between 60-80 bucks to go get a new one.

I just put one in my 87 4.2L and it was 74.99 at NAPA.

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Old 07-29-2012, 06:48 PM   #3
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the engine was out of a 94 Cherokee i did the engine + AX15 swap
it was working before repair the starter and suddenly didnt after i put the starter back
the spark was white - blue i guess and the gas was there and can smell it while trying to start the engine.
anyway i am still open for any suggestions.
btw is that ICM thing is the one that i connect the long wire out of the fuel rail harness with four pins?
cuz if it is its totally disconnected.
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Old 07-30-2012, 05:56 PM   #4
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Posts: 124
finally i manage to get the engine start by disconnect and clean all the engine sensors and plugs .
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