Good points Moe. So we're sort of back to my point from page 3 of this thread, one of the T's is either not allowing fuel into the bowls or the air vent is blocked and keep the pressure from equalizing and not allowing the bowls to fill.
Doug, do this easy test: attach a tubing to the bowl drain and open the drain screw with the petcock open and see if you can drain the tank. Do both sides, one at a time. You'll find the obstruction that way.
