40 hp YAMAHA with electrical problem

[spark plug]

I have a 40 hp Yamaha, 1996 model, 2 cyl. Only the bottom cyl. will fire. Have checked the plugs, I was told if it fires at all, it was not the power pack, and probably the coil. Is this my problem, or could it be something elese? Please reply.

 

[Ray Neudecker]

Re: 40 hp YAMAHA with electrical problem

Switch the wires to the coils and see if fire switches. If so its a bad coil, if not a bad CDI box.