I first tank of gas on my Hustler SD Kohler 7000 stop running when gas level was about half full. I spent hours on the internet trying to find out why it would not pump fuel from the tank. Replaced pump and filter, but still would not pump fuel from tank to crank. For some reason or another I decided to fill the tank to full position. Well, it cranked. Why is it only uses half it fuel capacity before having to refuel? The specs say it is a 3 gallon tank. At this rate I will always have old gas in the tank.