I have a Big Country 3493QBS thats a little over a year old. This past weekend was the first time using the pump to supply water to the RV. After filling the tank and turning it on low water pressure at all facuets. The winterizing valve is in the normal place. However the pump is trying to suck for the take and also the antifreeze suck line. It will pump little water though. I tried capping off the antifreeze line and then the pump will not pump any water. Loosen the plug up and it sucks again with low pressure and never enough to shut the pump off. Any suggestions on this?