Cummins/Onan 1B Series / 1B Series Plant — Testing the spark
Testing & diagnosis · ignition system
For the Cummins/Onan 1B Series / 1B Series Plant, from the Cummins/Onan operator's manual.
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Procedure
- Remove spark plug shield. Disconnect spark plug cable from spark plug.
- Hold this end about 3/16 inch from base of spark plug or cylinder head.
- Crank engine electrically or manually and note whether spark jumps the 3/16 inch gap.
- If spark fails to jump gap, check magneto breaker points and magneto coil.
Specs & values
- Spark gap 3/16 inch
Source: Cummins/Onan operator's manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.