HEI - No spark

My HEI upgrade had been working great. I left the Jeep sit for a few months while I replaced the floorboards. When I went to start it.....nothing. Engine cranks over strong, but when I pulled a plug and grounded it there was no spark. Anyone have some troubleshooting suggestions?

 

Simple things first....
Do you have 12v to the terminal on the distributor?
Is the terminal where power hooks up clean?
Is there moisture in the cap/rotor from sitting?
Is the coil hooked up properly? Clean connections?
Corrosion on the module terminals under the rotor?

 

Ok, did some checking. I have 12 volts at the distributor wire, but, while the engine is cranking it drops off to about 10. Is that enough voltage drop to make it not fire?

 

I think you should still get spark with 10v. You could get out the jumper cables to confirm.

It's a good idea to have a spare module in your parts box for trial rides. Get another module - you can use it for a spare even if it's not the problem now. You can grab one from the junk yard or go visit your FLAPS.

 

I wonder if you fried the module when welding? I was always told to disconnect the battery when welding on a vehicle.

Maybe not, but just a thought.

A Module is the weakest link in the popular HEI and gives no warning when failing.