No hot water when water pump is on.

I have a 2013 Winnebago 27rbds travel trailer, the hot water will not work while the water pump is on. If I turn on the water pump and let water pressure build in pipes and then turn it off the hot water will work until all water pressure is gone, once I turn the pump on the water will turn cold until I turn it back off at which point it will go back to hot until the pressure is gone again. The camper was brought straight from the dealership to a remote location where it is now, I have never had it hooked up to a municipal water system so I do not know how it would behave on one. Any help would be appreciated.