no start after alternator swap -

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post #1 of 8 Old 11-26-2010, 02:43 PM Thread Starter
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1989 WJ 
Join Date: Oct 2009
Location: RI
Posts: 2
no start after alternator swap

Hi All,

I'm turning to this group as I'm out of ideas as to why my 89 YJ with the 4.2 won't start after I swapped in a high output alternator. I know I have some electrical gremlins, thanks to the previous owner and some rodents, but I drove the Jeep this morning! Getting ready for plowing season, so thought I'd swap in a higher output alternator. Got it in fine, with only one incident. Even though I had disconnected the ground at the battery, I forgot I had a ground from the other negative terminal (marine battery). Touched the positive wire to the alternator while inserting the alternator and got a pretty good spark! Finished the install, and now the Jeep won't turn over. Have 12.5 volts at the battery, lights work fine. Cleaned the negative battery terminal and cable that I had removed and reattached. When I hit the ignition switch I hear, I believe, the solenoid click. I have not tried a jumper down to the starter yet, but it's getting dark and I'm too frustrated to think about this right now. Any ideas from anyone on what I should try next?

Thanks all.

Don89yj is offline  
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post #2 of 8 Old 11-26-2010, 02:49 PM
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1995 YJ Wrangler 
Join Date: Feb 2009
Location: Los Angeles. California. United States.
Posts: 4,910
Are you getting spark? The alternator generates power for spark to the coil. My guess is some part of that wiring got messed up, a fuse perhaps?
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post #3 of 8 Old 11-26-2010, 06:13 PM
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2013 JK Wrangler 
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Location: Grovetown, GA
Posts: 229
All cables/wires hooked up right and tight? Sounds like a lead is loose or not connected. May have blown a fuse, but it should still turn over.

2013 Wrangler Rubicon 2dr
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post #4 of 8 Old 11-26-2010, 06:23 PM
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1991 YJ Wrangler 
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Clean the + terminal also.


MJM Powder Coating
Elizabethtown Ky.
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post #5 of 8 Old 11-26-2010, 07:27 PM Thread Starter
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1989 WJ 
Join Date: Oct 2009
Location: RI
Posts: 2
I reinstalled the original alternator, unfortunately with the same result: won't turn over. All connections are correct, but will check and clean them all when it gets light. A quick look at the fuses didn't show any in the fuse box that were blown. Are there others I should look at?

thanks again for the responses.
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post #6 of 8 Old 11-26-2010, 07:33 PM
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1967 CJ5 
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Location: lake george NY
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Idk but what about the starter solenoid I had one go in my old Ramcharger and it had the same symptoms you seem to be having...
xWhite420wIDOWx is offline  
post #7 of 8 Old 11-26-2010, 09:21 PM
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1991 YJ Wrangler 
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Location: Elizabethtown
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You need to fill out your jeep info so we know what you have.


MJM Powder Coating
Elizabethtown Ky.
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post #8 of 8 Old 11-26-2010, 09:46 PM
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1990 YJ Wrangler 
Join Date: Jan 2009
Location: NA
Posts: 1,621
You were on the right track. The problem has nothing to do with the coil or ignition system. The engine is not turning over, so check the starting circuits all the way thru as you began. Start with the fat positive cable down to the solenoid to the starter and then back again. Did you lose your engine ground? It attaches to the side of the block behind the alternator. Make sure battery is charged and all the connectins and grounds are intact. Then, if still no cranking, jumper the solenoid and see if the starter spins.

Whatever happened was something that got disturbed as a result of the work you did. It is very unlikely that the starter decided to fail or something else decided to fail at this exact moment.

Let us know what you find.
plym49 is offline  

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