A very common issue is some blockage at the city water inlet point. There is wire screen attached to the hose rubber ring.
Right behind this screen is a check valve that can get stuck. Some times a push on it can clean up an issue. Remove the screen first.
Do you have a pressure regulator in the system, external or built-in?
Sometimes there is a three-way valve just inside of the city water connection that goes to either the coach system or allows filling the fresh water tank. If you have such a valve is it set right?
Is the water pressure good when you run off the pump and fresh water tank?
Fred & Denise (RVM157) New Mexico
2007 Excel Classic 30RSO & Coach House 272XL E450
2007 RAM 3500, Diesel, 6Spd Auto, SWD, 4x4, CC & LB