My truck wouldn't start the other day when I was leaving work. After a few mins of troubleshooting, I found that the center conductor of the distributor cap was roasted. Looks like it got so hot that plastic around it got all crispy and brittle. I have the Jacobs Off Road ignition, which puts out more than a stock setup, but never seen this before. Had a Supercoil on a different vehicle with no problems. Only about 5000 miles with the Jacobs setup. Anyone else seen this before? Maybe just a bad cap? High resistance in the center pin, plus lots of voltage equals lots of heat? Anyways, seems to be running fine now with a new cap, I'll have to keep an eye on it.

I've seen this on a few vehicles. It typically happens when the carbon element in the center of the distributor cap cracks or wears excessively. As the gap between the cap element and rotor grows, the spark jumping the gap gets hotter and hotter, further accelerating the wear on the element. Replace, and make sure the new cap and rotor don't get contaminated with any grease when you reinstall.

-Jeff

Had another no spark problem today, of course, at work when I was heading home. Truck wouldn't start, checked the distributor cap, looked good. Pulled a plug to check for spark, had buddy crank it and all of a sudden I had spark and truck fired and was running on 3 with one in my hand. <img src="/forums/images/graemlins/zombie.gif" alt="" /> I got home and checked the resistance on the signal generator, was a little high, so I replaced that, hoping it fixes the problem. Anyone had anything similar with a Jacobs ignition? <img src="/forums/images/graemlins/confused.gif" alt="" />

Still fighting the no spark problem. I installed the stock ignition so that I can just swap a few connectors from the Jacobs to the stock setup when the problem occurs. My question is, what is the little electronic pack that attaches to the side/rear tab of the stock coil setup? Couldn't find any pictures or description of it in the manual I have. Found that the truck wouldn't run unless it was electrically connected to the stock coil, so since my Jacobs setup is in the original location, I had to run a jumper from the electronic pack to the tab on the side of the stock coil. Just curious as to what that thing is, Thanks.

Little square-ish black thing with the blue and black wires going into it? Dunno, but I always figured it was some kind of resistor.

Yep, that's it. Truck won't run unless it's electrically connected to the side of the stock coil pack.

That there would be called a ballast resistor.