where the fuel hoses meet the big grommet going into the tank, pinch 1 fuel hose at a time while spraying some soap water on the black grommet I mentioned. Look for bubbles. Try pinch each hose(it would take too long to explain which proper hose to pinch….
This rubber grommet leaks air so you don’t have pressure pushing fuel up to the carb for full speed.
another test I try is turn the blower so the tanks is level or above carb So the carb doesn’t have to fight gravity to get gas.