Cummins/Onan — Quick Ignition Test
Testing & diagnosis · ignition system
From a Cummins/Onan service manual — check it applies to your exact model before use.
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Before you start
- HIGH VOLTAGE: do not touch the spark plug or wire during this test.
- Gasoline and LPG are flammable and explosive.
Procedure
- Park the vehicle in a well-ventilated area and leave the compartment door open.
- Make sure you cannot smell gas or gasoline vapors.
- Remove one of the spark plugs.
- Reconnect the spark plug cable and lay the spark plug on bare engine metal to ground it.
- Crank the engine and observe the spark.
- A strong consistent spark indicates the ignition system is probably functioning properly.
Source: Cummins/Onan service 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.