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Unread 02-24-2013, 08:25 PM   #1
YJSlave
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1989 YJ Wrangler 
 
Join Date: Apr 2008
Location: New Jersey
Posts: 119
No Spark Ignition Problems!

So I will try not to make this too long, but more info eliminates extra questions later.

89 wrangler 4.2L 5spd with weber carb, nutter bypass and CRT juice box ignition(TFI)
Last week the jeep would run fine and then after parking or shutting off by it self then on restart it would stumble, backfire, not idle, it sounded like it was not running on all cylinders.

I had it towed to a shop they cleaned the float bowl and the fuel filter and said it ran great, they held it over night and the next day it wouldn't start. They tried it all, timing, carb adjustments no good. It had inconsistant spark or none at all while timing it. I came in and asked if they checked the coil they said no. I had the stock coil still in place but not hooked up. I hooked it up and it ran like a top.

I assumed the ecoil on the TFI went bad, so I got a new one. Unfortunitly it ran the same, went back to stock coil till I could exchange the coil. Drove the rest of the week about 200 miles. So yesterday I returned it for a new coil, it ran for 30 seconds and it shut off. Now I can not restart or get a spark with either the stock coil or the TFI coil.

I am stumped, any thoughts? Also the starter has started to try to start and then spin free and clunk back into the flywheel. Any thoughts on that?

Help my DD Tacoma blew a head gasket so I have borrowed my brothers cherokee for a couple days. Need to get it running soon. It is not my week with vehicles!

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Unread 02-24-2013, 08:49 PM   #2
Old4X
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1990 CJ7 
 
Join Date: Nov 2008
Location: Ga
Posts: 5,120
Are you running a ballast resistor in the ignition circuit?
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418 miles on 19 gallons of gas. Can't beat the BBD !
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Unread 02-24-2013, 09:09 PM   #3
YJSlave
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1989 YJ Wrangler 
 
Join Date: Apr 2008
Location: New Jersey
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no I do not believe I am.
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Unread 02-24-2013, 09:23 PM   #4
Old4X
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1990 CJ7 
 
Join Date: Nov 2008
Location: Ga
Posts: 5,120
That is probably what made the stock coil run so well, then quit.

I am using an internally voltage controlled ICM that does not require the resistor, so I removed it. Full system voltage to coil at start and idle, but reduced as rpms increase. This is with a stock coil, no problems.

IIRC, the TFI coils do not require the resistor. You may have a bad ICM that is overdriving your coil and burning them up. Also, failing parts in the ignition system can lead to damage of the ICM.

The ICM really should have a dedicated ground, a poor ground can damage coils as well as the coil grounds back through the ICM.

I am not familiar with the CRT system, but it is vulnerable to the same maladies that cause similar ignition systems to fail. What distributor, ICM and coil are you running now? What are you using for a heat sink on your ICM?
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418 miles on 19 gallons of gas. Can't beat the BBD !
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Unread 02-25-2013, 07:14 AM   #5
Que89YJ
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1989 YJ Wrangler 
 
Join Date: Apr 2008
Location: Detroit, Michigan
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Did you run a seperate ground for the distributor when you did the nutter?
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Unread 02-25-2013, 11:26 AM   #6
YJSlave
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1989 YJ Wrangler 
 
Join Date: Apr 2008
Location: New Jersey
Posts: 119
Jeep was running the factory ignition control module. I did the nutter about 6 yrs ago. The TFI coil is housed in an aluminum case this is bolted to the jeep battery tray support arm and I figured that was the ground. I did try to add a ground to the TFI coil to a chasis ground. It didn't help with the spark.

Using the factory distributor with 6cyl F150 cap, rotor, coil. Factory ICM no heat sink.

Old4x what are you using for ICM? Since it looks like I need a new one
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Unread 03-04-2013, 12:30 PM   #7
YJSlave
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1989 YJ Wrangler 
 
Join Date: Apr 2008
Location: New Jersey
Posts: 119
Ok problem 1 solved, it was the ignition control module. I needed the jeep so I bought a new one at Napa. But will be doing HEI to complement my current TFI system. Will the TFI/HEI hybrid really be that much better?

Now the only issue is my starter. Sometimes it is fine other times it spins free then clunks into the flywheel. I am assuming it is a bad starter and not the flywheel. I was going to pick up a new starter any advice on a good replacement?
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