Ok I have a Model MT walker bought brand new in 2008 with a 20hp Kohler engine. As of yesterday my mower would not run. I replace the fuel filter and tested the fuel pump for vaccuum. I am not receiving any fuel from the tank. The tank is more than half full. I do not feel any vaccuum coming from the hose before or after the fuel filter. When I take the diaphram off the fuel pump, I have suction. Is there something I'm missing?