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Mystery spark loss in 83 k20

I have just finished putting in a new crate 350. New carb and everything else in my 83 k20. I will start the truck, it will run for about 5 to 10 minutes then I lose spark. I have checked and replaced the pick up coil, the ignition module and ignition coil. I have ensured it’s getting its 12 volts and no more than 14.5 when running. Still have the same problem over and over 4 times now. Any ideas?

Are you sure all the grounds between the engine and body/chassis are reconnected?


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What engine did the truck come with,
have you checked for voltage on the primary when the engine quits,
where physically is the ignition coil located relative to the exhaust manifold,
are these headers,
are they stock-type manifolds,
and have you considered heat shields?

Is the engine stock configuration? Do you know its specs?
Short block or long block?

What size is the new carb?
How did you adjust it?

Lastly, are you sure it’s spark you’re losing?

Your truck may have electronic spark control and all the potential failures that go with it. If your ignition module had only 4 pins ESC is not in your truck. Modules with 7 pins have ESC. And on a non ESC distributor the only external electrical connection is the ignition primary at the distrubutor cap. ESC distributors have a lead exiting the distributor bowl that are connected to the ESC module mounted either on the firewall or on the intake manifold.

Hey tester, that was the problem exactly. Cleaned up the connection to the body it was perfectly fine. Thanks man!


Deleted post.

Thanks for the followup post. It’s always good to hear a happy ending. :slight_smile: