Ok spears, ya got me. Kind of. If you have pressure on the carb inlet, then the carb is plugged. That is the immediate problem. You'll have to determine the origin of the crud, and take steps to eliminate that.

It looks like a general consensus that it's the fuel lines deteriorating, and replacement is warranted even if they are not. ( because they will ). Could also be the sock in the tank, on the pick up of the sending unit, or the fuel pump, or a break in the fuel line, causing the pump to suck air.