I had the same problem although I was not using the city connection. When I de-winterized, I could not get water to run although I heard the pump working. Finally realized it was my hot water tank by pass valve. Turned it the right way and voila, everthing worked.
Good luck!
Big Dave
2008 F350 Superduty 6.4 TD "Bumbles"
2007 Keystone Raptor 3814
2004 Polaris Sportsman 700 EFI
2008 Yamaha Raptor 250 SE
2007 Yamaha YZ85
2006 Polaris TB250
Assorted other toys
2 Boys who only know one speed