Look into the port the water gushed out of and see if there is something jamming the check valve disc open. It's not the pump. The check valve in the city water connector is stuck open or damaged. That's probably a lot cheaper than the pump, which sounds like it's working fine.
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'The Silver HamShack' (2007 International 22FB CCD 75th Aniversary model)
Multiple Yaesu Radios inside and many antennae sprouting from roof, ProPride hitch
2012 shortbed crewcab 4x4 Toyota Taco TV with more antennae on it