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Ignition System Tests

  1. If engine lacks power, does not start, or misfires, check pick-up coil voltage while cranking engine. See PICK-UP COIL RESISTANCE TEST  in this article. Voltage reading should be 1.3-2.0 volts. If not correct, check pick-up coil resistance.
  2. Ensure that pick-up coil-to-stator air gap is 0.014-0.28" (0.35-0.70 mm). Also check wiring and connections between pick-up coil and ignition control unit.
  3. Turn ignition on and check power supply at ignition control unit, by checking voltage between terminals 2 and 4 of ignition control unit plug. Voltage reading should be about 12 volts.
  4. if not correct, check voltage drop between terminal 2 and battery negative terminal. Also check voltage drop between terminal 4 and battery positive terminal.
  5. Connect ammeter to terminal 15 of ignition coil and ground. Turn ignition on, tester should indicate 0 amps after about 1 minute. With ignition on, connect voltmeter between terminal 15 of coil and ground.
  6. Voltmeter reading should be 12 volts. Turn off ignition and check coil resistance. See IGNITION COIL RESISTANCE TEST  in this article. If readings are incorrect, replace ignition coil.
  7. Check wiring from terminal 1 of ignition coil to terminal 4 of ignition control unit. Replace coil and ignition control unit if compound is running out of coil housing or if plug on top of coil is missing.
  8. Check resistance of spark plug wires, rotor, and shielded caps. Check distributor cap, rotor, spark plugs and spark plug wires for hair-line cracks. Check spark plug heat range, electrode gap, and condition. Replace parts as necessary.
  9. Start engine. If engine cannot be started, replace ignition control unit. If engine starts, connect ammeter between terminal 15 of coil and ground. Run engine at 950-1050 RPM. Meter should indicate 1.7-7.0 amps.
  10. If reading is too low, eliminate resistance in coil primary circuit. If reading is too high, replace ignition control unit. If reading is correct, check and adjust ignition timing. If timing is correct, ignition system is okay.
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