[BigLew]

Did you blow out the air vent line to the tank? Did you blow the ENTIRE fuel line Back towards the tank with the line detached from the tank? How old is the fuel line bulb and could the check valves be hanging up?

You are apparrently are not getting flow from the tank to the engine despite the engine's fuel pump pulling what fuel is available (the collapsed bulb.) be sure to blow the lines out in reverse flow fashion and replace any suspicious compnents. (I would be particularly suspicious fo the vent line because insects have been known to get into them and build some sort of nest/obstruction.) If it were me, regardless of what I believe I found, I would likely replace the bulb and their check valves in addition to any other components I suspected.

Just my 2 cents.