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post #1 of (permalink) Old 07-02-2002, 11:43 PM
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I have an 85 CJ-7 that I dropped a 401 into some time ago.
I had it running a while ago, and it suddenly died.
I checked all the obvious reasons this might happen, and am stumpped.
The engine turns over, but there's no spark!
I checked all the connections, the + is hot to the coil, and the - is definately grounded. There's just no spark from the coil wire.
I even replaced the coil.
The only time I have seen a spark is when the ignition is released to the "On" position from the "Start" position, there was a very small and brief spark.
Someone recommended that I change a "ignition switch" that's located under the dash "where the steering column meets". That doesn't seem to make sense to me, because when the key is turned to the on position, the + wire to the coil is hot...

All help would be greatly appreciated.


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post #2 of (permalink) Old 07-03-2002, 12:53 AM
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what ignition are you using?

if its a duraspark, then try another box.
if during your wiring testing installing phase, you mis wired the box it might been damaged.

it mostl likely sparks when you turn it from start to on, becasue it for an instant drops the primary voltage on teh coil ( basically what the ignition box does)

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post #3 of (permalink) Old 07-03-2002, 09:01 AM
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I havn't replaced it yet.
It's a Borg Warner.
So you think this might be it?
I'll replace it this evening, and see how it works...

I just put my new drive shaft on, and would like to try it out...
It's got a CV on it.

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post #4 of (permalink) Old 07-03-2002, 04:30 PM
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**I have an 85 CJ-7 that I dropped a 401 into some time ago.
I had it running a while ago, and it suddenly died.**

Suddenly dying is a sign of a catastrophic failure of some sort.
(Last one of these catastrophic 'Ignition' problems I helped with, the guy had changed the coil, the module, the distributor trigger and starter solenoid and it still wouldn't run, so after I looked at it, he put on a fuel pump and it ran fine...)

First a couple of questions...
1. What ignition do you have?
If the distributor vacuum advance is made of plastic, and there is a square 4 wire connector plus a ground wire coming from the module, you have a Prestolite ignition.

If you have points, you probably have the Delco distributor. We can work with that.

If you have a metal vacuum advance, and no breaker points, you probably have the Motorcraft distributor.
This is a very easy to upgrade ignition.

Here are a couple of tests.
1. Take a spark plug, wrap stripped 14 Ga. wire around the threads.
Secure the other end of the 14 Ga. wire to a good ground, like the battery negative terminal.
Pull the coil wire out, and stick the top of the spark plug in the top of the coil.
Have someone crank the engine while you can watch the spark plug.

If you get spark, you have a problem with cap, rotor, coil wire, ect....
If you don't get spark at the test plug, you have a bad module, trigger coil in the distributor, or bad wiring in between...

**I even replaced the coil.**

That should rule out the coil, now check the module...

**The only time I have seen a spark is when the ignition is released to the "On" position from the "Start" position, there was a very small and brief spark.**

This is normal. That's exactly what it's supposed to do. The coil is saturating, and it's getting ground.
If you have an electronic ignition, try a new module...
Make sure you get a good one, like from Borg Warner...
Modules will still pass in store testing and still be junk, using a known good module is the only way to correctly test the system.

**Someone recommended that I change a "ignition switch" that's located under the dash "where the steering column meets".**

Don't listen to 'Parts Changers'...
Find the problem before you start changing parts.

Junk Yard Genius is offline  
post #5 of (permalink) Old 07-04-2002, 12:11 AM
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I replaced the Ignition Module with a new Borg Warner, Tested the new coil at Auto Zone (tested fine), I tested all the wires to the coil, and replaced the Sylinoid.
I didn't bother with the Ignition Switch, because it just didn't make sense to me...
The Cap and Rotor are new, I've been thinking about the pick-up coil...

My distributor does have a metal vaccuum, no points...

Oh, I tried running a jumper from the + batt to the + Coil. Still no luck...

Any other ideas???

post #6 of (permalink) Old 07-04-2002, 01:21 PM
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Now we know you have a Motorcraft distributor with a DuraSpark module...

That advance plate with pick up is about $15...
Look for one with a brass center bushing.

Take off the distributor cap, rotor,
Use two screwdrivers to take the reluctor off, but take care to pry on the base circle of the reluctor and NOT the 'Arms'...
Pry it straight up. A little grease on the shaft first will make the reluctor move much easier.
Don't lose the little roll pin that keeps the reluctor in place, you will need that when you reinstall...

There will be a wire clip in a groove just above the center bushing.
Carefully take that larger wire 'C' retainer out of it's groove.

Now, remove the smaller 'C' clip from the vacuum advance arm on the advance plate.
Don't lose that little sucker either!

Take the two screws out of the vacuum advance housing, and remove the vacuum advance.

Now you should be able to lift out the advance plate and trigger coil assembly.

Clean the floor plate, and put fresh grease in the grooves. A synthetic 'Blue' wheel bearing grease works best.
(I like the marine kind because it's higher grade, and moisture resistant.)

Lube the inside of the new advance plate busing, and install it on the floor plate platform.
Clean off the larger wire clip groove and the top of the assembly, and install the larger wire clip in it's groove.

Reinstall the vacuum advance on the distributor housing, and reconnect the vacuum advance arm on the advance plate pin. Don't forget that little 'C' clip!

Replace the reluctor, and install it's roll pin.
Make sure the reluctor doesn't rub on the bottom! If need be, pry it up a little for clearance. It just needs to clear the bottom floor plate neck and advance plate bushing, nothing more.

Reinstall the rotor, distributor cap adaptor and/or distributor cap.

I usually test the pickup coils with the test plug method,
Leave the ignition switch in the 'Run' position, and wave a magnet around in front of the pick up, between the pick up and reluctor...
You should get trigger then...

You can also use a seat belt buzzer, wire it up, and lay it on the trigger.
This will simulate normal operating RPM...
But a seat belt buzzer can cost as much as a new pick up coil, and doesn't guarantee you will find the problem...
It's just a field test thing we use around here.

You can also line up the reluctor with the pick up coil, and tap on the side of the distributor. This should also cause a discharge at the test plug...

Have you cleaned all the connectors really well, and refilled them with dielectric grease?
Especially the distributor to module connectors?
This is the only way to keep these low voltage connections working...

Did you by any chance splice in a battery ground wire to the black wire from the module?
If the module isn't getting ground, it's not going to work, and the entire primary side of the ignition grounds through that black wire from the module.
It goes to the distributor and grounds through the housing, so if you don't have a good engine ground to the timing cover, you are NOT getting a good ground.

Splice in a 14 Ga. wire from the module black wire to the battery negative.
This will help your ignition even if it isn't the problem THIS time...
Junk Yard Genius is offline  
post #7 of (permalink) Old 07-04-2002, 02:00 PM
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I really appreciate all your time thinking about my problem...
I did a "Nutter Bypass", but did not run a ground wire to the black wire in the ignition module. The black wire is run directly from my distributor...

Out of curriosity, would this, or my distributor cause my coil not to arc?

Thanks again,
post #8 of (permalink) Old 07-05-2002, 02:25 PM
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Re: No spark from my coil...

Anyone else got any ideas?

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