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Old 08-27-2012, 03:32 PM   #1
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89 Wrangler Dead - Ignition Module?

Hello all.

My Wrangler died today. :-)

I had recently replaced the fuel tank, and because of a planned upgrade in under the hood, did not replace the fuel pump. Because I assumed Murphy's law, I expected this to be a fuel pump problem, but I don't think it is. We can hear it run and smell fuel when cranking...so it appears to be a spark issue.

The Jeep recently (yesterday) started missing once it warmed up. In any gear when you'd push it (over 3000 RPMs) it would miss, or at least thats the best way I can discribe it. Once it cooled down, it seemed okay. Never stalled, just would miss and shudder a few times and then be okay. The best description was probably from my daughter who said it hiccuped...which is pretty accurate.

I've read through the forums and thought about a new cap/rotor and plugs/wires. When it died, a fellow Jeeper rescued me and suggested it might be the ignition coil. When I called to check on the availability of one, the auto parts guy (also a jeeper) said he would replace the ignition module first...9 times out of 10 that is the problem.

Thoughts from any of you? The ignition module is about $115, which isn't huge, but I'd hate to jump right into that when it is a dist/rotor problem.

The truck would not start once it stalled today. I give it a better then 50/50 shot of starting once it cools down, but we will see.

I've ready through the forums and found lots of leads, but I'm trying to narrow it down. Lots of recommendations for just a tune up....which is why I was going to do plugs, wires and distro.


Thanks in advance!

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Old 08-27-2012, 04:25 PM   #2
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could be, take in the module and get it tested.

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Old 08-27-2012, 05:29 PM   #3
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You've gone this far with it I would replace the coil along with the ICM. I think the parts guy is right. When my 89 started giving me trouble I replaced it and no more trouble. Don't forget it's 23 yrs. old. As far as testing, I think most times that won't tell you much. They seem to go and cause problems when you add heat. I think you're losing spark. If you need a tune up you should do that anyway.
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Old 08-28-2012, 09:39 AM   #4
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What Kik said. If its time for a tune up go ahead and do it. It may solve your issue or at least eliminate that part and it isnt an expensive undertaking.
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Old 08-29-2012, 01:48 PM   #5
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Thanks for the help. I ordered the ICM and will give that a go. The Coil is in stock, so if I still have problems, I can easily go get that and through it on.

I'll also be buying a new set of plugs, wires and distro cap and rotor. I will install stuff and test to see if the problem was resolved with each part and report back in case this helps someone else in the future.
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Old 08-31-2012, 08:40 PM   #6
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Okay, it's a frustrating day.

Coil replaced, ICM replaced, plugs, wires, cap and rotor....all replaced.

Same thing. Agh.

I'm back to thinking it has to be a fuel delivery problem, but after spending over $200 on unneeded parts, I think another $200 on a pump is going to have to wait. So frustrating.

Chris
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Old 08-31-2012, 08:54 PM   #7
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Have you checked the fuel pressure?
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Old 09-01-2012, 10:22 AM   #8
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Have not checked fuel pressure as I don't have anything to check that with.

I had to leave it sit overnight and this morning it fired right up. Drove home and let it idle in garage. Idled without a problem for nearly half an hour and through several tstat cycles (so its not over heating), then it just stopped. No throttle at all, not in gear, just idling in neutral.

I think it has to be a fuel problem, but I'm not experienced with TBI. I may have to take it in.

Chris
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Old 09-01-2012, 12:47 PM   #9
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Quote:
Originally Posted by meyerc89yj View Post
Have not checked fuel pressure as I don't have anything to check that with.

I had to leave it sit overnight and this morning it fired right up. Drove home and let it idle in garage. Idled without a problem for nearly half an hour and through several tstat cycles (so its not over heating), then it just stopped. No throttle at all, not in gear, just idling in neutral.

I think it has to be a fuel problem, but I'm not experienced with TBI. I may have to take it in.

Chris
I didn't realize you had a 2.5 FI. Partly my fault for not asking, but partly your fault for not providing engine info. I know you don't want to spend more $ but your symptoms, now knowing you have FI, is a classic fuel pump issue which is, runs fine cold and then under load or hot there isn't enough pressure provided for what is called for. You most likely have a bad electric in tank fuel pump. The regulator could also be bad. Unfortunately, if the pressure can't be tested you'll have to throw a few more parts at it. However, I believe the most likely source is the fuel pump.
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Old 09-01-2012, 05:16 PM   #10
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Yea, sorry for not being more clear.

I asked one of the guys at the auto parts store and he suggested spraying some carb cleaner around the intake to see if the engine raced, if it did, there could be a leak.

Well, I did...and it killed instantly. I think I will make an appointment to have it diagnosed at a garage and go from there.

Certainly frusterating. On the plus side, if it is the pump, at least the project won't involve breaking rusty bolts as I replaced the tank less then a month ago and all bolts are new.

I originally suspected the pump, but a number of people told me that the problem, if it was a pump, would make more sense if the tank was near empty, since mine is full to the top, the theory is that it should remain cool submerged in fuel.

Eitherway, I need a diagnosis with tools I don't have, so I think that is my next step.

Chris
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Old 09-01-2012, 07:14 PM   #11
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The parts guy is talking about a possible vacuum leak, and, that's really old school regarding a carb'd engine. I don't think that would affect your issue. The empty or full tank has nothing to do with the pressure it's putting out. It's the heat affecting the fuel during the combustion process. If there isn't enough fuel (pressure) there can't be proper combustion which would cause your symptoms, especially under load when the engine is calling for more fuel. I think you were correct originally suspecting the pump. I think if you drop the tank and replace the combination pump/sending unit you'll solve the problem.
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Old 09-01-2012, 09:09 PM   #12
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Kik,

I think you are probably right. I dug out the Hanes manual today and found my way around the fuel rail. Tomorrow I'm going to pick up a fuel pressure test kit and see what I'm getting.

I guess if it is bad, at least I know the problem is the pump and another $200. If the pressure is good, then I keep digging.
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Old 09-07-2012, 10:27 PM   #13
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I went to my mechanic because he's always good about taking care of me

He was going to test the fuel pressure, but said he noticed the crank position sensor looked rough. Tested it and that was the problem. Jeep runs good again.

I know that was one suggestion before, but so were coil, Icm, plugs, wires, map, tps, etc... Glad its solved...that was a frustrating problem!

Chris

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