Cummins/Onan — Gasoline Carburetor Adjustment
Adjustments
From a Cummins/Onan service manual — check it applies to your exact model before use.
Applies to: Cummins/Onan MCCK
Before you start
- Do not force needle valves against their seats; this can bend the needle.
Procedure
- Warm up engine. With no load, turn idle fuel adjustment out until speed drops slightly below normal, then in until speed returns to normal.
- Apply a full load to engine.
- Loosen packing nut and turn main adjustment in until speed drops slightly below normal, then out until speed returns to normal.
- Tighten packing nut.
Tools required
- Tachometer Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Full service-parts list: Cummins/Onan MCCK →
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.