Electrical problem, no spark.

[Griffin6]

Okay, I’m new to the site and hope I am asking this question in the right place and forum. I have a 1983 CJ7 that came from the Toledo factory installed with the AMC 4-cylinder engine. I know, those didn't show up until 1984, but what can I say? Even I was surprised when I picked up the Jeep in fall of 83 after returning from a tour of duty in Germany.

I've kept the Jeep virtually stock except for adding a Weber 2barrel Carb about 4 years ago. Its been running great. Good pickup, especially for a 4 cyl. A few weeks back, it was hard to start, finally caught although running rough. I turned it off and it remains dead. I replaced the ignition module as that was usually the culprit in the past. No go. I traced the system and all wiring is good. I did a nutter bypass a half dozen years ago and it's been running great. I have a lot of new spare parts so I started by replacing the coil, coil connector, solenoid (even though it turns over great) plugs, cap, rotor, and the pick up coil in the distributor. Bottom line, no spark at the plugs. I used one of your threatpds and checked the power to the ignition module and that is fine. I probed the coil connector with a test light (bulb, not LED) and the red wire is bright when in run and start. The green wire is very dim in Run, and I get no light on the green wire in start. Knowing the ignition modules are notorious for being bad out of the box, I installed a second new spare. Still no spark. I'm stumped. Suggestions?

 

[Belizean]

I had that engine in my 84 for over 35 years and I loved that simple engine with a Weber and the last 8 - 10 years with a MSD coil and CD box that reawakened the engine. I got close to 1/4 million miles before replacing the 4 with a 6. What kind of mileage does your engine have ?

 

[Griffin6]

I had that engine in my 84 for over 35 years, and I loved that simple engine with a Weber and the last 8 - 10 years with a MSD coil and CD box that reawakened the engine. I got close to 1/4 million miles before replacing the 4 with a 6. What kind of mileage does your engine have ?

I have just over 200K. I did have the head rebuilt a few years ago and other than some routine maintenance, and tender loving care, it's been a reliable. I'm the first to admit, the AMC 4 banger has been a good little engine. Now that I have some time on my hands, I am considering upgrading to a 6cyl engine, like you.

 

[Belizean]

Has the timing chain and sprockets been replaced ? Right at about 140,000 miles mine started running like at idle and stalling when pulling up for a light or stop sign. That caused the timing to go a little crazy.

 

[NP435]

I have just over 200K. I did have the head rebuilt a few years ago and other than some routine maintenance, and tender loving care, it's been a reliable. I'm the first to admit, the AMC 4 banger has been a good little engine. Now that I have some time on my hands, I am considering upgrading to a 6cyl engine, like you.

I had a similar problem with my AMC 258 i6 / 4.2l 6 banger, solution was a hot wire to a switch on the dash then to my HEI distributor, if you dont have HEI this may not cure you.

 

[Griffin6]

Has the timing chain and sprockets been replaced ? Right at about 140,000 miles mine started running like at idle and stalling when pulling up for a light or stop sign. That caused the timing to go a little crazy.

Yes, I changed the sprocket and timing chain when I had the head rebuilt. Using a timing light is near impossible to get right. I get a much smoother idle and more power doing so by ear.

 

[Griffin6]

I had a similar problem with my AMC 258 i6 / 4.2l 6 banger, solution was a hot wire to a switch on the dash then to my HEI distributor, if you dont have HEI this may not cure you.

If you can believe it, I still have the stock distributor although I have rebuilt it a few times.

 

[CJ]

Replying from your DM.
The ignition system on a CJ is relatively simple.
In case I missed this, is the coil good?

To ohm out an automotive coil, disconnect the negative battery terminal, remove the coil's high-tension lead, and set your multimeter to the 20k Ohm setting to test the secondary winding, then to 200 Ohms for the primary winding, checking for readings within the specified ranges.
Is the rotor actually turning while cranking?
Is the any spark at the spark plug while cranking?

Is there any spark (even faint) while cranking?
Is the rotor turning while cranking?

 

[Griffin6]

Replying from your DM.
The ignition system on a CJ is relatively simple.
In case I missed this, is the coil good?

Is there any spark (even faint) while cranking?
Is the rotor turning while cranking?

Hi, yep, it really isn’t a complex ignition system and that is why I am so stumped.
It ran great for years with minor tending loving care. I suddenly had a hard time starting it and then it ran rough. I turned off the key and when I tried to restart it, it took a long time to kick over. I ran it around the neighborhood and then came home, parking it. Since then, it cranks but will not kick over.
I started with the basics and then got more aggressive, replacing parts.
Ultimately, I discovered there was no spark.
I replaced the ignition module, coil, coil connector terminal, coil wire and spark plug wires, distributor cap and rotor, (I did check and the rotor turns while cranking), I put a new stator in the distributor, and even for good measure, put in a new starter solenoid and fuel pump. (I had the parts). Still no spark.
I tested the power to the ignition module and it is good. I ran a direct ground wire from the battery to the ignition module and put in a second module since they are known to be bad out of the box.
I tested the plugs for spark against the block and with and inline spark tester. Nothing. Not even a weak spark.
I probed the coil connector both while in the run position (Red wire Bright/green wire dark)
When cranking, the red wire remains bright, but the green wire remains dark.
Maybe here is where someone can help me. I thought the red wire in The coil connector is supposed to be dim when in run and bright when cranking (mine remains bright both in run and cranking).
The green is supposed to show bright in run, flashing when cranking! Mine shows no light in run and no light when cranking.
Before I tear out all the wires, maybe someone can give me a hint as to how to take care of the gremlin in the system. Thanks!

 

[WHATROAD]

My electrical problems in the cj have been, mostly, a broken ground wire somewhere. The last one to do me in was the ground around the front marker/turn signal light. rusted screw holding the ring on. I don't know just how many grounds amc thought they needed, or installed, but I'm willing to bet they were covering their butts for how connections went out with just electrical tape. From the factory! I'll bet they didn't think so many of them would be driving around this many decades later. Its the decades later that cause grounds and taped connections to give way. Another $.02. Good luck.

 

[TeamRush]

This isn't as difficult as you might think.

Get yourself an incandescent bulb, connect it to the coil connector. Crank the engine.

If it flashes the ignition trigger AND module are working. Then you suspect the ignition coil or high voltage side of the ignition, coil wire, center terminal in the cap in specific.

If it doesn't flash, then it's the low voltage side. Trigger in distributor or module.

When cranking, there should be battery voltage getting to the coil. This comes from the 'I' (Ignition) terminal on the starter relay.

When the key is in the 'Run' position you should get a 'Dimmer' light at the coil terminal.

When the key switch is in the 'Run' position there is a resistor wire between power source & ignition coil. This is keep the module alive which will overheat if it gets battery voltage full time.

I can't remember off the top of my head what the distributor trigger resistance (Ohms) is supposed to be, you'll find it in the manual.

 

[CJ]

This isn't as difficult as you might think.

Get yourself an incandescent bulb, connect it to the coil connector. Crank the engine.

If it flashes the ignition trigger AND module are working. Then you suspect the ignition coil or high voltage side of the ignition, coil wire, center terminal in the cap in specific.

If it doesn't flash, then it's the low voltage side. Trigger in distributor or module.

When cranking, there should be battery voltage getting to the coil. This comes from the 'I' (Ignition) terminal on the starter relay.

When the key is in the 'Run' position you should get a 'Dimmer' light at the coil terminal.

When the key switch is in the 'Run' position there is a resistor wire between power source & ignition coil. This is keep the module alive which will overheat if it gets battery voltage full time.

I can't remember off the top of my head what the distributor trigger resistance (Ohms) is supposed to be, you'll find it in the manual.

A simple phone call to just chat and a legend crashes the party!

 

[TeamRush]

Respectfully, a Jeep doesn't have a 'Ground'. It's all DC Circuits. Circuit means full lap back to point of origin.

While 'Ground' is commonly used vocabulary, it references 'Earth Ground' and Jeeps don't have a Ground Rod.

If you look at military vehicles of the same age as a CJ, you will find the military required Negative wires to electrical components. This is because they often sit for years, are used hard for decades and expected to work.

The lack of a Negative wire to complete the circuit comes from manufacturers, it saves the cost of the copper on each unit which can be a million a year.

Being old enough to have worked in shops when these vehicles were new, It's also guaranteed repair shop money. If it lived between 12 & 36 months (and usually did) then it's an easy fix for the shop, and easy money for the dealership.

These issies were well know to the shops so they knew exactly where to look, and if it failed in warrenty it was an in & out job, just clean the 'Ground' and send it back out. Worst case senerio it took a short 'Ground' wire.

................

"Electrical Circuit", a full lap, back to point of origin.

Steel is a horrible conductor of DC current. Copper does a MUCH better job, and if you ran Positive wires, it would have been really easy to run a Negative wire also.

Jeep bodies are spot welded or bolted together. From frame to body there are rubber electrical insulators, same with drive train to frame.

This means you have a lot of steel parts flying in very close formation. Paint, rust, crud all contribute to keep electrical contact from happening.

............

If you have the DuraSpark ignition, you will find a 'Quirk' in it's wiring.

It was built as a stand alone system so it could be transplanted into about anything... A hold over back to when Ford made industal engines for pumps, light generators, engines for farm equipment, etc.

The module/ignition coil 'Grounds' (Negative side of the circuit) connects to the engine block THROUGH THE DISTRIBUTOR HOUSING.

That's the reason your distributor cinnector has 3 wires instead of 2.

This means your ignition circuit DEGRADES as the distributor to engine mechanical connection builds up oil residue. Mechanical connections are not necessarily electrical connections, and if it's making electrical connection there's no guarantee it's a fully functioning electrical connection...

It's a Gears AND Wires thing instead of just Gears alone...

 

[Griffin6]

Thank you. I printed out your posts and am heading out to the garage! I will let you know.