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Home >> GMC >> 1987 >> Forward Control 4.8 T, Standard >> Repair and Diagnosis (Single Page) >> Engine Performance >> Ignition System >> Ignition System - HEI (CARBURETED Models) >> System Testing >> Intermittent System Problems
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Intermittent System Problems

  1. Check spark at 2 plug wires using test plug. If no spark occurs, refer to ENGINE WILL NOT START  section. If spark occurs from one or both spark plug wires, check pick-up coil with ohmmeter. Refer to PICK-UP COIL  in COMPONENT TESTING section in this article.
  2. Replace pick-up coil if defective. If unit tests good, check for dwell increase from high to low RPM. If dwell did not increase, replace electronic module. If dwell did increase, and trouble is not found, check fuel, coil and plug wires, and cap and plugs.
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