no petrol flowing to engine?

i have been given a peugeot speedfight it wasnt running but after closer inspection on it i noticed it has a spark so i moved on to check the fuel and it seemed to have no fuel getting into the carb i used easy start and the bike starts and runs perfect but then cuts out when i stop spraying, i then checked the vaccum pipe from the vaccum tap by suckin the pipe petrol flows to the engine what could cause this pipe to not be sucking