Which "battery?" Coach usually has a "House" battery and that's the one which usually cranks the generator. It has to be Good, Fully Charged, Good Connections, and ***ON***. I mention "ON" because there's usually a Battery Switch for the House and that usually operates a Relay that actually handles the load.
Most of us have ONAN generators. Generac is probably second, followed by Kohler. To get help with Generac, you might be better off to look at smokstak.com which has a Generac section.
I can't confirm, but I imagine a Generac of the 1994-vintage has a Logic Board like ONAN does, and that part could have failed. Also if it's sat three years without the gas removed, I'm all but certain the carburetor is gummed up.