What is the setup you have for controlling the water pump? And the pump does not 'pressurize' the tank, it just is self-priming and suctions the water out to the pump, then pumps it to the outlet.
Have you located the "Water Pump" On switch? Or do you have the multi-position control in the service bay (where the water hose is connected)? Pics would help us help you...
2016 Tiffin 40 QBH
2015 38RSSA, traded
2005 TK3 #1869, 10 yrs of memories,
2017 F450 KR--one more Ford is it
2009 F450 4x4-died; 2010 F450-retired