Cummins/Onan — Idle Mixture and Frequency Adjustment
Adjustments · carburetor
From a Cummins/Onan service manual covering: 4.5 MCE, 5.0 MCE, 6.5 MCE. Check it applies to your exact model before use.
Applies to: Cummins/Onan 4.5 MCE, Cummins/Onan 5.0 MCE, Cummins/Onan 6.5 MCE, Cummins/Onan MCE engine
Before you start
- Disconnect voltage and frequency sensitive devices before adjusting.
Procedure
- Disconnect all loads and check no-load frequency.
- Turn idle mixture screw clockwise until frequency drops, then counterclockwise until it drops again.
- Set screw for highest possible stable frequency.
- Check output voltage: 123-132 VAC at 63 Hz or 105-115 VAC at 52 Hz.
- Push adjustment limiter cap over mixture screw head.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- 123-132 VAC at 63 Hz
- 105-115 KuduParts $58.00 FridayParts $59.99 VAC at 52 Hz
Full service-parts list: Cummins/Onan 4.5 MCE →, Cummins/Onan 5.0 MCE →, Cummins/Onan 6.5 MCE →
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.