Cummins/Onan — Adjusting the Garretson Regulator
Adjustments · gas fuel regulator
From a Cummins/Onan owner's manual covering: 10HQ, 10HQ-150R, 15HQ, 15HQ-150R, 15HQ-4R30. Check it applies to your exact model before use.
Applies to: Cummins/Onan 10HQ, Cummins/Onan 10HQ-150R, Cummins/Onan 15HQ, Cummins/Onan 15HQ-150R, Cummins/Onan 15HQ-4R30, Continental F162 engine
Before you start
- A soap bubble over the regulator outlet will not accurately test for regulator closing.
Procedure
- Connect a manometer reading up to 14 inches water column to the regulator test hole near the inlet; turn gas on.
- Turn closing adjusting screw (G) inward just until manometer reading remains constant when outlet is repeatedly covered and uncovered.
- Close gas supply valve, remove manometer, bleed air from line, install test-hole plug, open valve.
- Secure hose between regulator nipple and carburetor inlet with clamps.
- Operate engine to assure quick starting.
Tools required
- manometer Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Lock-off pressure 4 ounces (7 in. water column); operates at incoming pressure 2 to 4 ounces
Full service-parts list: Cummins/Onan 10HQ →, Cummins/Onan 10HQ-150R →, Cummins/Onan 15HQ →, Cummins/Onan 15HQ-150R →, Cummins/Onan 15HQ-4R30 →, Continental F162 engine →
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.