Cummins/Onan — Idle Speed - Adjustment
Adjustments · fuel system
From a Cummins/Onan owner's manual covering: 6C8.3, 6CT 8.3, 6CTA8.3. Check it applies to your exact model before use.
Applies to: Cummins/Onan 6CTA8.3, Cummins/Onan C Series, Cummins/Onan 6CT8.3 engine
Procedure
- Industrial: loosen locknut and back out the bumper spring screw.
- Speed should drop 20-30 rpm as the screw is backed out.
- Loosen locknut; set idle screw 20-30 rpm less than desired speed.
- Turn idle screw counterclockwise to decrease rpm; clockwise to increase.
- Turn bumper spring screw in until desired idle speed is obtained.
- Tighten the locknut.
- Automotive: loosen locknut and turn screw counterclockwise to raise rpm, clockwise to decrease.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Speed should drop 20-30 FridayParts $58.50 rpm as screw is backed out
Full service-parts list: Cummins/Onan C Series →
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.