Can you see the fuel line where it connects to the carb? Look for bubbles in that fuel line; if there are bubbles, try to trace it back to where they start - at a T, filter, tank, or hole in fuel line.

All the above stuff makes sense to me, except that I've got a 46AX and a 55AX, and a 120AX for that matter, in planes with the tank well above the carb and haven't had any issues related to tank position.