The clicking sound can also be a lack of proper voltage under load at the starter motor caused by a weak battery or poor connections or cables. You should check the voltage at the large terminal at the starter motor while trying to start the genny. It should be above 9.6 volts.
Another possibility is that the engine for the genny has excessive drag or is seized due to mechanical problems.
2008 Itasca Meridian 37H & 2015 Flagstaff T12RBST
2011 & 2012 Len & Pat's "One lap of America"
27K miles & 41 states in 13 months - Woo Woo
Yellowstone Lake 6-1-2012