Damn Thermoquads.

Ok squirter don't squirt, glass fuel filter is dry................where did the fuel go??????? Downhill, all the way back to the fuel tank.
The Check valve, aka one way valve (in the mechanical fuel pump) is leaking. fuel is sneaking by it and running back into your fuel tank.
Hit it with some carb spray......eng starts, fuel pump pumps, and everything is ok.........

If you have the Carter Super Pump you can take it apart and try and clean the check valve......if it stock factory. Time to try another one!

Its NOT your carbs fault, there is no fuel in it.