Is the tank vented? Does it draw from the top a line hangs down in or draw from the bottom? What do you mean it floods when you pour fuel into the line, does the engine run and flood out or is fuel running out of the carburetor?
Try setting your jug high and run a line direct to the carb, gravity fed. Fix your leaks first and you must have a needle and seat or float problem as the bowl should not fill that far anyway, and that would explain the flooding. When you can get it to run gravity fed you can work backwards to the pump and tank to eliminate problems.