[rohrmann]

Besides the possibility that the screen on the city water inlet fitting that could be clogged, I have also seen the check valve in that city water fitting stuck closed or almost closed, which would allow the pressure to equalize on both sides, but flow would be very restricted. Sometimes, you can take a small screwdriver and poke at the valve to make sure it is free, and do that with the pump turned off so you don't get a bath. Another question, have you just hooked up a hose to the water spigot and turned on the water? That will tell you if the water volume from the spigot is good or not.