The Mercury primer bulb will work as long as the hose size is correct.
Yamaha hoses will plug in either way around. Is yours correct. Also some primer bulbs don't have a discharge valve (they rely on the valves in the engine's pump). If the line is full of air they have a hard time pushing it out if the carb is full. You have to remove the line from the engine, depress the ball in the end of the hose and pump the bulb. Be careful of the fuel spray!
