Suspected moisture problem

Adam632 · Sep 6, 2024

Schurkey said:
Connect an INCANDESCENT test light or jumper wire to ground. Test light preferred as it's easier to hold onto.

Start warm, running-properly engine.

Rub the probe of the test light or the alligator-clip of the jumper wire along each spark plug wire from distributor cap to spark plug. If at some point the engine starts to misfire, and it's related to the grounded probe, you've got poor insulation on the plug wires.

Then, mist the top of the ignition coil (only) with water from a squirt-bottle. If the engine misfires, you've got a defective ignition coil.

Lastly, mist the distributor cap (only). If the engine misfires, you need a different cap.

Start the engine on a dark, moonless night--or inside a dark garage. Look for "Corona discharge" on the plug wires. No, not spilled beer. It's an eerie glow indicating failing insulation.

Reinstalling the Vortec distributor is a pain in the tuckus, but given the failure rate, it's probably worthwhile to yank it out for inspection. You'll need a scan tool to get it re-positioned properly. "I" would check the cam offset number before pulling it out, maybe it's off but not far enough to set a code. That would increase the spark voltage, making life harder on the insulation of the entire secondary ignition circuit.

Okay thank you! I will look into all of these things… anything else?

Schurkey · Sep 6, 2024

Adam632 said:
anything else?

Sure. But tell us the results of the testing that's already suggested.

Suspected moisture problem

Adam632

Newbie

Schurkey

Supporting Member

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