This tractor has the Onan BF MS 16 hp engine. There is a fuel pump mounted to the back side of the carb. When I got it there was an external fuel pump in line from the tank to the carb. bottom of the fuel tank site about 6" lower than the carb. Is the fuel pump on the carb a push only type pump or does it have enough lift to draw the fuel up the 6" required to use the bottom 1/3 of the tank? Service manuals don't say anything about this, only the repair and cleaning.