Failure To Start Test
CAUTION:
Perform IGNITION SYSTEM STARTING TEST first. Failure to do so may result in lost diagnostic time or incorrect test results.
- Remove coil secondary wire from distributor cap and position it 1/4" away from good engine ground. Turn ignition on. Using special jumper wire, intermittently ground coil negative terminal. Watch for spark at coil wire. See Fig 1.
- If there is spark, proceed to step 5). If there is no spark, turn ignition off. Disconnect 10-wire connector from spark control computer. Turn ignition on. Using special jumper wire, intermittently ground coil negative terminal. Watch for spark at coil wire.
- If there is spark, replace spark control computer. Check if engine will start. If there is no spark, measure voltage at coil positive terminal. Voltage should be within one volt of battery voltage. If there is no voltage, check and repair wiring between battery and coil positive terminal.
- If there is voltage at coil positive terminal, measure voltage at coil negative terminal. Voltage should be within one volt of battery voltage. If there is voltage, but no spark when grounding coil negative terminal, replace ignition coil. If there is no voltage, replace ignition coil.
- If there is voltage but engine will not start, hold carburetor switch open with a thin cardboard insulator. Measure voltage at carburetor switch. Voltage should be within one volt of battery voltage. If there is voltage, proceed to step 9).
- If there is no voltage, turn ignition off. Disconnect computer 10-wire connector. Turn ignition on. Measure voltage at connector cavity "2". Voltage should be within one volt of battery voltage. If there is no voltage, turn ignition off. Check for continuity in wiring between connector cavity "2" and battery. Repair wiring as necessary.
- If there is voltage, turn ignition off. Check for continuity between connector cavity "7" and carburetor switch. If there is no continuity, check for open circuit in wiring between carburetor switch and connector cavity "7". If there is continuity, check for continuity between connector cavity "10" and ground.
- If there is continuity, replace defective computer. Repeat step 5). If there is no continuity, check for open circuit in wiring. If wiring is okay, but engine still will not start, proceed to step 9).
- Reconnect computer 10-wire connector. Disconnect distributor harness connector. Connect distributor harness connector terminals "2" and "3" using a jumper wire. Turn ignition on. Hold coil secondary wire near a good engine ground.
- Make and break connection at either end of jumper wire several times. There should be a spark at coil wire. If there is spark at coil wire, but engine still will not start, replace Hall Effect pick-up.
- If there is no spark at coil wire, measure voltage at harness connector terminal "1". Voltage should be within one volt of battery voltage. If voltage is as specified, turn ignition off. Disconnect computer 10-wire connector.
- Check for continuity between 10-wire connector cavity "9" and distributor harness connector terminal "2". Check for continuity between 10-wire connector cavity "5" and distributor harness connector terminal "3". If there is no continuity performing these checks, repair wiring harness. If there is continuity, replace computer. Repeat steps 9) and 10).
- If there was no voltage in step 11), turn ignition off. Disconnect computer 10-wire connector. Check for continuity between connector cavity "3" and distributor harness connector terminal "1". If there is no continuity, repair wire and repeat steps 9) and 10).
- If there is continuity, turn ignition on. Check for battery voltage between 10-wire connector cavities "2" and "10". If battery voltage is present, replace defective computer. Repeat steps
- and 10). If battery voltage is not present, computer is not grounded. Check ground wire and repeat steps 9) and 10).