There is obviously a problem with the generator. You should have a full 120 volts (approx.) when the generator is running. I would check for circuit breakers on the generator. If that is not the problem, you might need to consult with a professional for that brand generator. There might also be a main power disconnect switch somewhere on your motor home.
For the original OP, you should also be checking for open circuit breakers as Herman and Brett mentioned. Whenever I lose power to outlets, I have a circuit breaker tripped. For example, when I am running a small ceramic heater and the coffee maker, if I try to toast some bread I will trip the breaker to the front of the coach. This is a likely candidate for you as well. Electric heaters draw a lot of power.
FMCA #F431170, GS #822128658, Escapees SKP #112655
2006 Country Coach Magna (525 HP Cat C13 1650 torque, Alison 4000 6 speed tranny), 2012 Jeep Liberty