Water pump pumping backwards

2oldman wrote:
Only two things are likely: hoses are on wrong, or wires are reversed.

Since most water pumps are "diaphram" style, the direction of the rotation of the motor is of no consequence with respect to wiring.

The water pump is working normally The city water inlet and the pump outlet are connected by a common "T" fitting. (or connected to tow inlet ports on teh same Manifold )

The check valve in the city water INLET has failed..

There are two schools of thought

1: If you remove the screen washer you will see a white plastic "Button" pressing it will ruin the valve
2: Pressing it may ix the valve

Suggestion: Do not worry about 1 cause i you can not 2, then 1 it is.

rv2 has a nifty idea there.

I been down that road and now have a common ole PVC screw in plug/stopper that I got from Lowes.

I bet you have one of these laying around. Screw in into the water inlet and turn the valve to the off position. Then check the pump.

You can use this untill you decide to replace the check valve. If Ever. :B

Yep....internal check valve on fill connection stuck open.

Tap the socket where the hose attaches. Sometimes the check valve sticks. When they stick open the system will not pressurize and can pump water out the inlet line.

The check valve just at the wall is open. Normally pressure from the fill hose overcomes the check valve spring, and the tank fills.

Connect a hose to the fill connection, then pinch the hose and see if things work fine inside the RV. If everything works fine, it's an easy fix to replace that check valve.

Only two things are likely: hoses are on wrong, or wires are reversed.