Remove the fuel inlet nipple on the carb and see if the fuel passage was
miss-drilled like this one on my GMS .47.

If it is like mine, it is easy to redrill and open the restriction. Also....use a piece of
fuel line....connect it to the muffler pressure nipple that goes to the tank. Blow through
it, and make sure the nipple is not restricted into the muffler. Some of these were
not drilled correctly, and did not allow enough pressure to the tank. This and the
carb inlet nipple restriction were the cause of the problems.

FBD.