Check the fuel line to and from the genset to the fuel tank. Pin hole leaks introduce air into the system. IMO, the fan belt can create a lot of problems.
Like most all systems in a motor home, Preventive Maintaince (PM) is a recommendation in all the manuals. Yet, a lot of folks ignore it. Nothing breaks until you start to use it. I have always suggest that if your coach has set up for several months, the weekend before you leave on a trip take the coach out to a local campground and live in it for a couple days and nights. Chuck B 2004 Windsor