I have the 55 ax and I have the fueler you showed at the very top. I have had no problems with mine and I fill till I see fuel in the vent line, sometimes a little goes in the muffler but it does not cause a problem. Just before you see the fuel in the muffler line you will see air bubbles, that tells me that i am getting really close to full and that it is time to stop. I also found on my nexstar that if I lift the front up just 3 inches I get more fuel in but that would depend on where the vent line sits in the tank.