How do you FILL fresh water tank
Gravity fill port
OR
FILL Valve that you swap from City Water/Normal to FILL position ??
Fill Valve...
They can fail (o-ring) or leak thru
Pump has an internal 'check valve' (diaphragm) that can fail/get held open
Some times just running /using pump will clear any debris on diaphragm and allow it to fully close
***With City Water OFF/Pump ON but all faucets off....listen for pump to run short cycles
Check Valve leaking the pump will turn on when pressure goes down then turn right back off when pressure is restored.
Fill valve.....pump may have hard time developing full pressure. May take longer to turn off when faucets are closed
If you have easy access to pump suction side...disconnect the pump suction line.
Turn on city water supply and see if water comes out of pump suction side
