For all of who have trouble getting the engine to draw fuel. Use a three-line tank. One line goes from the felt clunk to the carb (no breaks, no T, no filler, no chance for an air leak). One line is the fill/drain that goes to the bottom of the tank. One line is the vent (at the top of tank). After you are done flying, just drain the tank. The feed line to the carb stays full of gasoline because the diaphragm pump makes a seal. When you go to start the engine, gas is already in the carb and in the line - easy choking and the diaphragm pumps better when wet with gas.