Propane Conversion

6.5 Kw Onan converted to propane The generator's carbuerator still functions in the normal way with this conversion, mixing air and fuel into the combustion chamber. You will need some special propane regulation and safety equipment, available from any generator shop that sells and services large propane generators (Onan, Kohler, Winco, etc.).

We guarantee that this procedure will void your generator's warranty!

We ARE NOT RESPONSIBLE for any property damage or personal injury resulting from this procedure...we are simply relaying information to you about how OTHERS have successfully converted their generators. If you are stubborn and foolish enough to try the conversion described here on your expensive generator, you are on your own. Others have done it, and it does work! But if you don't have the basic knowledge to work with pressurized propane, DON'T EVEN START THIS PROJECT! Are we clear on this?????

Converted 6.5Kw Onan Genset

Examine the above photo carefully, and identify the new parts for the conversion!

  • First, obtain a Garretson propane regulator (see photo above) for propane generators from your local generator shop. This regulator will adjust propane flow depending on the load requirements from the genset, via a vacuum sensor (that is built-in). The Garretson goes between your normal propane regulator and the genset. You can make this thing run without the Garretson, but only at constant load...if your load were to change (such as batteries filling up, a piece of power equipment turning on, etc.) you would have to immediately adjust your needle valve (as with our previous, rough conversion instructions) or the generator would stall. This would be very difficult to do, and the Garretson takes care of the problem automatically.
  • Next, for safety reasons buy a solenoid propane cutoff valve (see photo above) and install it between the normal propane regulator and the Garretson. Wire it to the generator's ignition, so that if the ignition switch is OFF, so is the propane.
  • Install an adjustment valve (see photo above) between the Garretson and the carbuerator to make lean/rich adjustments while the genset is running.
  • Buy a diffuser end to stick into the carb venturi...or build your own (see photo below). The homemade version is simply a piece of copper tubing, crimped off at the end, with holes drilled into it to diffuse the propane into the venturi. It works, and costs nothing.
Homemade Propane Diffuser

Homemade Propane Diffuser to Insert into Carb Venturi

  • Many parts can now be removed from your generator. Save them in case the whole deal doesn't work out for you! The carbuerator float can come out, as it will just rattle around and get in the way. Ditto with the choke (or just leave it in and keep it all the way open)...the Garretson regulator has a button you can push that provides full gas pressure during starting, though this is normally needed only during cold weather starts. Adjustments for starting can also be made with the new gas control valve you installed.
  • That's pretty much it...our neighbor has had great success with his converted Onan. If you have any more information or advice that we could add to this page, please let us know! Propane is an excellent generator fuel, especially during cold does not suffer from condensation and thickening problems like gasoline and diesel.