Cummins/Onan — Governor Adjustment
Adjustments
From a Cummins/Onan owner's manual — check it applies to your exact model before use.
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Before you start
- An adjustment too close will cause hunting; a fuel mixture too lean will also cause a hunting condition.
Procedure
- Run the engine about 15 minutes to reach normal operating temperature.
- Check the governor arm and linkage and the throttle shaft and lever for binding and for excessive slack or wear.
- Tighten any loosened screws which mount the variable speed governor control levers.
- Adjust the length of the linkage by rotating the ball joint so the carburetor throttle shaft stop just contacts the underside of the carburetor bowl.
- Adjust governor spring tension by the adjusting nut for the desired speed and lock with the second nut.
- Adjust governor sensitivity by moving the stud and bracket toward or away from the governor shaft.
- Always recheck the speed adjustment after a sensitivity adjustment.
- Set the throttle quadrant to match the throttle lever at electric POWER position.
- Set the carburetor throttle stop screw.
- Set the vacuum speed-booster.
Tools required
- Tachometer Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Speed drop from no load to full load must be within 100 rpm
- Governor speed limits 3050 rpm minimum to 3200 rpm maximum
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.