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post #1 of (permalink) Old 07-27-2002, 12:40 PM Thread Starter
 
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CJ - Engine catches then dies

85 CJ - 258 - stock ignition

I'm in the process of putting my Jeep back together after some body work. I went to start it today, and found that the engine would catch, but immediately die as soon as the key was released to the Run position. It doesn't even idle, simply "quits".

I haven't done the TR upgrade yet, because I wanted to make sure that it would run first.

Here's what I have noticed (and I'm no electrical wizard)

1.) On the coil harness, there are two wires (red w/tr) that connect to the coil. One of these wires is supposed to be connected to a capacitor (per TR's diagram for the Motorcraft ignition) but has rotted away from the capacitor. Is this necessary right now? Does this cap come into play during the TR upgrade?

2.) I originally had the factory tach, but disconnected when I removed the dash because it didn't work. The wires are dangling there (bad idea, I know!!! - I will be fixing this when the dash is reinstalled.)

3.) I don't have +12v at the red w/tr wire to the coil with the key in the run position. From searches, I understand that +12v is needed here - where does this wire come from/how can I get +12v (jumper wire???)

4.) Ignition module has NOT been tested, worked fine last season and I have not done any modifications or cutting of wires to/from the module.

5.) I have spark while cranking, tested with bare wire wrapped around the threads of a plug and grounded. Does this mean that the module is working properly?

From this, I can safely assume that the engine will not run because of the lack of +12v at the coil with the key in the run position? Could I use a jumper wire from the + battery terminal to the + post on the coil to test without frying anything?

Any and all help is appreciated.
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post #2 of (permalink) Old 07-27-2002, 08:27 PM
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Re: CJ - Engine catches then dies

You've got the problem isolated to the 8.7 volt resistor wire lead... It's either blown open, or the voltage suppy has been interrupted to that wire. Trace it back and I'm sure you'll find the error.
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post #3 of (permalink) Old 07-27-2002, 08:33 PM Thread Starter
 
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Re: CJ - Engine catches then dies

LEVE,

Thanks. I'll trace the wire back tomorrow and see if it's broken/fried/etc.

In my original post, I had mentioned that the other wire originally had connected to a capacitor mounted to the coil bracket. What is the purpose of this, and is it necessary for the ignition system? Once I've smoothed out the wiring problems, I will be doing the TR upgrade. Is this wire/capacitor needed in the upgrade?
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post #4 of (permalink) Old 07-27-2002, 08:57 PM
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Re: CJ - Engine catches then dies

I'll quote TR on this one:

<blockquote><font class="small">In reply to:</font><hr>

The "Condenser" is actually a Capacitor, and it's purpose is to buffer the high and low voltage swings in the electrical system when the ignition fires.
A failed capacitor is usually burned up internally, and just doesn't work anymore.
If you have a catastrophic failure, it will actually blow apart, but that is VERY rare.

Using a capacitor will help keep the noise out of the radio and other electronic equipment like computers.

There is one on most TFI coil arrangements from the factory, and the junk yard is the best place to find the coil bracket, coil, connector, and condenser for your application. You can usually get them for cheap....


<hr></blockquote>

On your system it will work without it... but I'd leave it in the sytem.
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