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Unread 02-18-2011, 01:09 PM   #46
95mudman
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1995 YJ Wrangler 
 
Join Date: Jan 2010
Location: new jersey
Posts: 27
The CEL has been on for months prob due to other issues but could bad caps in the comp even make me not have spark? As you said...I will check the coil tonight to see if its getting anything. I just dont see how they could be related to eachother. Im gonna replace the caps anyways since they are not hard to do. Maybe ill get lucky lol. Thanks guys!

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Unread 02-21-2011, 01:09 PM   #47
the1sasquach
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1994 YJ Wrangler 
 
Join Date: Feb 2011
Location: fort polk, La
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thanks a ton for the write up replaced capacitors with a lil patience and a couple of hours work she running like a dream for only $6 bucks
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Unread 12-09-2011, 03:45 PM   #48
IdabJeepin
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1993 ZJ 
 
Join Date: Jan 2011
Location: Rigby, Idaho
Posts: 72
Here to help keep this thread alive. I just replaced the three capacitors (220 uf 35VDC) in my 93 4.0 ZJ and my jeep is alive. My only frustration was having a POS for a soldering iron. But eventually it all worked out and my Jeep started this morning at 6 degrees above zero. No more waiting one minute to 5 minutes for the check engine light to come on. It took me several hours reading many threads and less than an hour to remove the ECM, replace the 3 capacitors and reinstall the ECM.
Many thanks to Jeep Forum and the input from several Jeepers.
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[B][SIZE="1"][FONT="Book Antiqua"][COLOR="DarkSlateGray"][SIZE="3"]93 ZJ 4.0 IL6[/SIZE]
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Unread 12-20-2013, 05:53 PM   #49
marley4hope
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1991 XJ Cherokee 
 
Join Date: Dec 2013
Location: Hartsel, CO
Posts: 1
I'm having similar issues with my 91' 4.0L. My CEL comes on sometimes and when it does I can hear the fuel pump prime and the vehicle starts, however when it doesn't come on the pump doesn't prime and vehicle will not start. Probing the fuel pump harness shows intermittent voltage which I assume coincides with whether the CEL comes on or not. I performed all of the tests and when I check pin 9 on the PCM connector it shows 12 volts regardless of whether the ignition switch is in the on position or not. Should pin 9 show voltage without the ignition in the start position? If not, could my ignition switch be bad? Could I have wiring problems that would cause this? Am I missing something or possibly performing these tests wrong?
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Unread 12-20-2013, 06:36 PM   #50
Que89YJ
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1989 YJ Wrangler 
 
Join Date: Apr 2008
Location: Detroit, Michigan
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Pin 9 is a direct battery feed and is hot all the time. If the cell does not come on and you have power to 3/9 then you need to repair the ecu.
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Unread 01-05-2014, 12:52 PM   #51
DTNJEEPER
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1994 YJ Wrangler 
 
Join Date: Mar 2012
Location: lansing, MI
Posts: 8
repair was spot on thank you!!! need to drive in this blizzard to clear walks for work. no worries now!! MANY PROPS!! note, i had to replace caps twice not sure why didnt bother to test to find why. for 5 bucks why bother? detailed info made it easy to try the second time. i just knew that this was spot on
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Unread 06-21-2014, 03:07 PM   #52
ma345to
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1994 YJ Wrangler 
 
Join Date: Jun 2014
Location: Saddle Brook, New Jersey
Posts: 2
hard to start even after the CEL comes on

Hello, everyone, this is my fist post onto this forum.

I have been driving a 1994 YJ Sahara, 4.0L, manual transmission, for about a year, and I love it. But now I have a problem similar to this thread. I have read the posts and thank you all for the invaluable info. Although my problem looks similar, I noticed some differences too. My jeep hesitates to start even after the CEL comes on... My mechanic has changed the fuel pump, but nothing has changed. And now he is saying that the engine control computer has to be changed, but I am not sure. So, what do you think?
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Unread 06-21-2014, 03:35 PM   #53
Que89YJ
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1989 YJ Wrangler 
 
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Did you do the repair on the caps? Does the check engine light come on or does it take a while south the ignition on for it to lite.
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Unread 06-21-2014, 07:50 PM   #54
ma345to
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1994 YJ Wrangler 
 
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Location: Saddle Brook, New Jersey
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Thank you, Que89YJ, for your quick reply, and I am sorry for the ambiguity.
No, the CEL does not come on at first, but I hear the clicking noise. When the CEL comes on finally, the clicking sound stops... I haven't replaced the caps yet since I am not sure yet if I can do it myself.
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Unread 06-21-2014, 08:28 PM   #55
Que89YJ
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1989 YJ Wrangler 
 
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Location: Detroit, Michigan
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It its really simple. Find someone that can and give them a few dollars. You might as well because you will be spending the money on another ecu anyways.
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Unread 12-30-2014, 04:25 PM   #56
SimplyTron
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1995 YJ Wrangler 
 
Join Date: May 2008
Location: Maryland
Posts: 40
Just used this to fix my 95 YJ. I was getting no CEL with the key on, long cranks, then when it did start it misfired for a min or so before it leveled out. It would start back up right away but if you let it sit for more than 15 mins it would do it all over again. I followed everything he said, checking all the fuses and pins, leading me to replacing the caps in the ecu. The only problem I had was getting the leftover solder out so I could get the new pins through. I used a "bulb" desoldering tool and it did the trick. I will say make sure you have a new tip for your iron with a fine point. Other than that it was easy, she fires right up now. Thanks so much.
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Unread 01-14-2015, 12:06 AM   #57
dochoffiday
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Does this only work for YJ?

Does this only work for YJ's or is this true for TJ's as well?
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Unread 01-14-2015, 08:58 AM   #58
Que89YJ
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1989 YJ Wrangler 
 
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If you don't see a cel that is always where you need to start. The ECU is a totally different critter and no the repair doesn't apply. Look at the tj section of the forum for guidance.
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Unread 03-23-2015, 04:25 AM   #59
Jonny Jeep
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Quote:
Originally Posted by dochoffiday View Post
Does this only work for YJ's or is this true for TJ's as well?
Quote:
Originally Posted by Que89YJ View Post
If you don't see a cel that is always where you need to start. The ECU is a totally different critter and no the repair doesn't apply. Look at the tj section of the forum for guidance.
I found this thread after following a link from a UK forum and since the question has been asked, the same does apply for TJs. The PCM is different of course, but the capacitor problem does exist. Though that doesn't necessarily mean that it is dochoffiday's problem.

http://www.jeepforum.com/forum/f9/19...rting-2901058/
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Unread 03-23-2015, 11:10 AM   #60
mike134
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1989 YJ Wrangler 
 
Join Date: Aug 2014
Location: Cleveland, OH
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The repair may end up applying to the TJ. They early models are probably getting to the age of capacitor failure as well... All capacitors fail in time, hopefully for them, the newer chip sets are not as sensitive as the YJ's.
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