Why is water coming out the city water hookup when pump is used?

[Wayne O]

My hose that I have hooked up to the city water hookup got a hole in it and was spewing water. Until I could get a new hose, I decided to put water into the tank and just use the pump for the night. However, when I turn on the pump water comes out the city water inlet like it is a faucet. I've used the pump before and didn't have this issue. Looking for ideas of what I'm doing incorrectly.

[A32Deuce]

Check valve stuck open in city inlet. See if you can remove the screen and push in on the check valve to get it to seat. Spring loaded.