I think one of the first things to do if you going to use some magic in a can (Sea Foam). Is remove the fuel line on the generator. You may have to add a length of fuel line to reach into a gallon can. Mix your magic in a can with a gallon of fuel whatever there recommend ratio is. And draw from the can, really no use treating 25 gallons or more of fuel in the motor home tank. Myself being a old timer I still treat carbs the old way and that's mix 6 parts of gasoline to 1 part of ATF. For the generator mix one gallon. Start the generator let it warm up and run it under full load till you use a 1/2 gallon of fuel. Then shut it off and let it sit overnight. Start the next day and again run under full load till all fuel is gone. Repeat once or twice if you need to. If that doesn't help, you need to rebuild the carb.