I haven't been on the forum for a while and I have been bad and haven't taken care of my RV for about as long. My wife and I haven't used it for about 5 years and I use to go out and start it every ot...
if you have a E350 ford chassis then you should have a drain plug on the bottom of the tank...if so remove the plug and let what ever is in the tank drain out into a bucket ..the first thing that will come out is the water trapped in the tank replace the plug and pour a cupl gallons of diesel fuel or kerosene through the tank to clean the inside of the tank..