Water tank over filling
I have a 2003 Windsor. At first I thought the ball valve went bad and was letting water go past and filling the fresh water holding tank while using the city water. I disconnected the line that goes to the tank and plugged the outlet on the ball valve side. The on board pump doesn't hold pressure and cycles like there is a big leak but I can't find one. Even though I disconnected the supply to the tank and I am using the city water, the holding tank fills and over flows. So my question is, could the water be back flowing through the on board pump from the city water? Any help to find the problem will be greatly appreciated.
2003 Monaco Windsor 40 PST
2015 Chevy Equinox
Full timing in search of the good life