Kohler 12RES / 8.5RES — Fuel Conversion Procedure (natural gas to LP vapor)
Adjustments · Multi-fuel block
For the Kohler 12RES / 8.5RES, from the Kohler operator's manual.
Applies to: Kohler 12RES, Kohler 8.5RES, Kohler CH20 engine, Kohler CH 740 engine
Before you start
- Do not adjust the factory-sealed fuel-metering adjustments on the fuel block.
- Explosive fuel vapors can cause severe injury or death.
- Accidental starting can cause severe injury or death.
Procedure
- Place the master switch in OFF, disconnect battery charger power, disconnect battery (negative lead first), and turn off fuel supply.
- Remove the hose clamp and fuel hose from the hose fitting in the fuel block.
- Remove the hose fitting from the natural gas outlet port in the fuel block.
- Remove the plug from the LP port, clean it, apply fresh pipe sealant, and install it into the natural gas outlet port.
- Clean the hose fitting, apply fresh pipe sealant to the threads, and install it into the LP port.
- Slide the hose onto the fitting and secure it with the clamp.
- For 12RES only: connect the DSAM leads together for natural gas (disconnect for LP vapor).
- Connect and turn on the new fuel supply; recheck the master switch is OFF.
- Reconnect the battery (negative lead last) and reconnect battery charger power.
- Start the generator set by moving the master switch to RUN and check for leaks with a gas leak detector.
- Move the generator set master switch to the AUTO position.
Tools required
- Gas leak detector Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Full service-parts list: Kohler 12RES →, Kohler 8.5RES →
Source: Kohler operator'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.