On the Liberty there is a squirrel cage fan motor behind the radiator for the generator. If this is cycling on and off (as mine was doing in OSH) during generator operation then it's time to take a peek under the bus. There's a really good chance that the baffle is missing. This baffle directs the hot air away from the intake side of the generators radiator, causing the blower motor to overheat and shut down for a limited time.
A new baffle is available from Liberty for a mere $350 Lewbucks.
Mike