Cummins/Onan — Spark Check
Testing & diagnosis · Ignition
From a Cummins/Onan service manual — check it applies to your exact model before use.
Applies to: Cummins/Onan HGJAA, Cummins/Onan HGJAB, Cummins/Onan HGJAC, Cummins/Onan HGJAD, Cummins/Onan HGJAE, Cummins/Onan HGJAF
Before you start
- Ensure no flammable fumes present and area well ventilated
Procedure
- Remove the spark plugs.
- Reconnect the spark plug cables.
- Ground side electrodes to bare metal on engine.
- Crank the engine and look for spark across each plug.
- Replace plug if spark weak or inconsistent.
- If still weak, test ignition coil resistance.
Specs & values
- Spark plug gap 0.025 in (0.6 mm)
Full service-parts list: Cummins/Onan HGJAA →, Cummins/Onan HGJAB →, Cummins/Onan HGJAC →, Cummins/Onan HGJAD →
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.