Cummins/Onan — Carburetor Adjustment (Gas Fuel)
Adjustments · Gas carburetor
From a Cummins/Onan service manual — check it applies to your exact model before use.
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Procedure
- Set main adjusting screw about 1-1/2 turns open.
- Set idle adjusting screw about 1-1/4 turns open.
- Start and warm up under average load.
- Final adjust main screw with full load: turn in until voltage or speed drops, then slowly outward until normal and steady.
- If more than 1/2 turn out after normal to prevent surging, adjust governor for less sensitivity.
- Final adjust idle screw after load disconnected.
- Weighted choke should just close but open freely with air stream. Adjust choke screw if fitted.
Specs & values
- main 1-1/2 turns
- idle 1-1/4 turns
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.