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Home >> GMC >> 1985 >> Forward Control 7.4 W, Standard >> Repair and Diagnosis >> Engine Performance >> Ignition System >> Ignition System - HEI (Federal) >> Testing - System Tests >> Intermittent System Problems
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Intermittent System Problems

  1. Check spark at 2 plug wires using Spark Tester (J-26792). If no spark occurs, go to ENGINE WILL NOT START  procedure. If spark occurs from 1 or both spark plug wires, check pick-up coil with ohmmeter, Refer to testing pick-up coil in TESTING - COMPONENT TESTS .
  2. If pick-up coil is defective, replace it. If it is good, check for dwell increase from high to low RPM. If dwell did not increase, replace electronic module.
  3. If dwell did increase, and trouble is not found, check fuel, coil and plug wires, also cap and plugs.
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