I have A '85 Sierra with HEI distributor, all was running well, until I shut it off and now I have no Spark. I have replaced module, RFI wiring harness, cap, button and coil. Nothing worked until I replaced RFI wiring harness. It started and made it about a mile before it died again. All it will do is turn over and not fire. I am at my wits end. I can only figure that the distributor is grounding somehow, but I cannot figure out where or how. It has a ECM under the dash that controls the distributor only. The Quad is strictly mechanical. Any Ideas or suggestions is greatly appreciated.

 

It sounds as though you have a short in one of the harnesses. You need a multi meter and a HUGE pail of patience. Start testing for live shorts.