This may sound like a truly dumb question but,,, On the old NV fuel tank mount the tube on the left site of the tank, the taller one goes all the way to the bottom of the tank, the short tube on the right seems to go to the middle of the back of the tank.. If I fill the tank from what would logically be the output tube fuel immediately runs out of the tank, Also if I use what appears to be the output tube for draining the tank I do not get all the fuel out. Help me out which of the two tube is which?