just to add to the first reply-check two things. you should check the float in your center carb-while your at it check all three. If as in the first reply you need petcock gaskets- www.partsnmore.com is the place to go for them. Your local yamaha shop probably won´t have them, and if they do-just hand them your wallet. as a note-You should set your fuel to on...prime will allow gas to flow at all times-which could be flooding your engine. In the on position, fuel should only flow when the engine is running because a vaccuum is formed which draws the fuel through the line.