[rverdlm]

There is no check valve between the tank and the pump. If you have water in the tank and you remove the input line from the pump water should run out. If it does not then there is a restriction in that line. another thing to check is to be sure the tank is vented. Remove the tank fill cap. If that helps then the tank vent line is plugged. It can also be a bad pump. Try feeding it from a different source. I hooked a hose from a bucket and fed it directly into the pump which in my case proved the pump was bad. I took the pump to CW and they replaced it with a new one.