HOW TO PREVENT VARNISHING IN YOUR GENERATOR

Varnish is the gummy residue that forms in the carburetor when fuel breaks down. Fuel varnishing clogs and stops up the small passages in the carburetor, making the genset start and run poorly, even though it may have low operation hours.

1. Treat Motor-home fuel tanks with a fuel stabilizer such as OnaFresh-GLXP Fuel Preservative Stabilizer or Sta-Bil Fuel Preservative and Stabilizer. In cold climates, avoid filing the tanks for storage late in the fall or in the winter. Cold weather fuel has additives to make it vaporize easier. This property also make the cold weather fuel evaporate out of the generator carburetor easier, leaving behind varnish.

2. After the Motor-home fuel tanks have been treated, run the generator long enough to draw the treated fuel into the RV genset carburetor. This normally takes about 10-15 minutes. Or, if your genset is so equipped, you can drain the fuel bowl by placing a small container under the carburetor and opening the fuel drain. Check the operator manual for complete draining instructions. If the genset has a fuel inlet shutoff, turn it off. Remember to put a reminder note on the RV genset ignition switch that the fuel supply has been turned off.

3. If you cannot drain the fuel from the carburetor, run the genset on a monthly exercise program under a full load. Genset Monthly Exercise Program: Operate Onan gasoline generators at a minimum of 50 percent capacity (2000 watts for a 4000 watts generator) for two hours at least once every four weeks. Small electric heaters and hair dryers make excellent loads for your genset exercise program.

4. Fuel varnishing is a result of time, temperature, and fuel evaporative properties. Filling the tanks with high octane gas will not prevent or reduce varnishing. Fuel stabilizer additives combined with regular genset exercise, or draining of fuel from the carburetor before long-term storage, are the most effective ways to reduce varnishing issues.