It sounds like you haven't got the needle valve opened far enough (it's only running out the prime) so open it another turn and try again. But first make sure there's nothing blocking the fuel line. Best way is to take the needle right out and blow fuel from the tank and out the open end of the needle valve. It should flow quite freely. With the battery connected it should keep running even very rich so as a starter I'd suggest opening it about 3 or 4 turns.