Cummins/Onan 1B Series — Testing the spark

Testing & diagnosis · Ignition system

For the Cummins/Onan 1B Series, from the Cummins/Onan owner's manual.

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Procedure

1. Remove spark plug shield.
2. Disconnect spark plug cable from spark plug.
3. Hold cable end about 3/16 inch from base of spark plug or cylinder head.
4. Crank engine electrically or manually.
5. Note whether spark jumps the 3/16 inch gap.
6. If spark fails, check magneto breaker points and magneto coil.

Source: Cummins/Onan owner'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.

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