When I review accident reports for the Used Aircraft Guide, I’m struck by how often pilots mismanage the fuel system. Usually it’s running one tank dry and not figuring out how to get fuel flowing to the engine from a tank that has fuel. From time to time a pilot pumps fuel overboard because he doesn’t understand that on a fuel-injected engine, fuel and fuel vapor is returned from the engine-driven fuel pump to one of the fuel tanks.
On some airplanes, the return fuel and vapor goes to a designated tank rather than the tank the pilot has selected to get fuel to the engine—notably on tip-tank Cessna twins and early model Bonanzas. If the tank that is receiving return fuel and vapor is full, the excess will be pumped overboard, reducing the range of the airplane.