Cummins/Onan — Electric Governor Preliminary Adjustments
Adjustments · Electric governor (optional)
From a Cummins/Onan service manual covering: 4BT3.9, 4BT3.9-GC1, 4BT3.9-GC2, 6BT5.9, 6BT5.9-GC1, 6BT5.9-GC2, 6CT8.3, 6CT8.3-GS/GC1, 6CTA8.3, 6CTA8.3-GS/GC1, 6CTA8.3-GS/GC2. Check it applies to your exact model before use.
Applies to: Cummins/Onan 4BT3.9, Cummins/Onan 6BT5.9, Cummins/Onan 6CTA8.3, Cummins/Onan 4BT3.9 engine, Cummins/Onan 6BT5.9 engine, Cummins/Onan 6CT8.3 engine, Cummins/Onan 6CTA8.3 engine
Procedure
- Set frequency adjust (engine speed) potentiometer to mid position and tighten locking nut.
- Set I potentiometer one division from zero.
- Set Gain potentiometer at the third division from zero.
- For isochronous operation turn Droop potentiometer fully counterclockwise.
- Turn droop screw to approximately 40 for 3 percent droop.
- Turn droop screw to approximately 80 for 5 percent droop.
Tools required
- Screwdriver Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- I potentiometer: one division from zero
- Gain: third division from zero
- Droop: approximately 40 = 3 percent, approximately 80 = 5 percent
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.