Kohler — Fuel Metering Valve Adjustment Procedure
Adjustments
From a Kohler service manual covering: 12RES, 12TRES, 8.5RES. Check it applies to your exact model before use.
Applies to: Kohler 12RES, Kohler 12TRES, Kohler 8.5RES, Kohler CH20 engine, Kohler CH 740 engine
Before you start
- Adjusting fuel metering valves on emission-certified gensets may void the emission certification. Only trained authorized technicians may adjust.
Procedure
- Disable genset (master switch OFF, disconnect battery charger).
- Remove oxygen sensor plug from exhaust manifold and install oxygen sensor.
- Connect oxygen sensor to engine starting battery, control module, and voltmeter.
- Reconnect battery charger, start genset, and run to normal operating temperature.
- Apply rated load; measure oxygen sensor output voltage (potential to ground).
- Adjust fuel metering valve to obtain specified oxygen sensor output.
- Seal metering valve adjustment screws with thread sealant.
- Remove load and cool genset 5-10 minutes; stop genset.
- Disconnect battery negative lead first; allow exhaust to cool.
- Remove oxygen sensor and reinstall exhaust plug with antiseize; reconnect battery negative lead last and battery charger.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Oxygen sensor reading 8.5 kW: natural gas 2.40 ±0.05 VDC, LP 2.25 ±0.05 VDC
- Oxygen sensor reading 12 kW: natural gas 2.60 ±0.05 VDC, LP 2.60 ±0.05 VDC
Full service-parts list: Kohler 12RES →, Kohler 12TRES →, Kohler 8.5RES →
Source: Kohler 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.