CUMMINGS, ONAN GENERATOR

Hello, I am called Richard Adams, I have got a Gasoline Generator 4000 Watt Rating 120 Volt . Magnetic circuit breaker & fused DC circuits (to protect wiring) 125" generator set output leads CUMMINGS, ONAN GENERATOR This came out of my RV which has been hooked up directly an rv park, so i haven't had a need for it. I have not used it in 3 years. Carburetor has been cleaned and adjusted, NEW SPARK PLUG.