the rubber gasket between the carb and the tank is called a diaphram.
it pumps fuel up to the carb, try putting in a new diaphram and that
should fix it. if your primer bulb is the least bit deteriorated replace
it also. ..... in some cases, the tube that the carb slides onto gets
loose or blows the gasket where it attaches to the engine block, that
little gasket cost little but can cause problems if bad... also snug up
the head bolts,the ones by the ex tend to loosen... good preventative
maintenance is to take off the sheetmetal and clean the grass out of the
cooling fins, this is a good time to check the intake tube and gasket...
lucas