harley4275 wrote:
Mine had a 90 degree kink in the hose right near the tank . Unscrew some of the coroplast under the trailer near the tank and look inside with a flashlight to see if yours is kinked.
Or put a pail of water inside and suck up that water thru your winterising length of hose near the pump. If it pumps good then you have a kink in the hose from the tank.
I had the same problem when winterizing (which comes through an inlet on the back of the trailer). That's why I'm fairly confident that the problem is somewhere at the pump itself (blocked screen, failing pump, etc...).