help with identifying a mercury outboard engine

[todd281]

I just acquired my first mercury outboard and am having trouble identifying the year and model . The cowl says its a 650, and 70 HP. The cowling also says Thunderbolt Ignition. It is a 3 cylinder ,with 3 coils, and has two carbs. The only id plate I see , is on the front of the motor, in between the mounting clamps. The only numbers on it are the serial no 5353056. It has no spark at this time and without knowing the correct information, I can not look up the wiring diagrams. Thanks for any help.

 

[racerone]

I would think that it is a 1979 model.-------It is the serial that is used when looking for parts.----Year does not interest most shops / parts desks.

 

[todd281]

Thanks for the reply. I have been searching online for a wiring diagram , but without knowing the year I am unable to find the correct one. So far all the diagrams I have seen have a 7 wire harness, my engine only has 5 wires , plus the main battery wires

 

[racerone]

Where did you buy the motor ??---Yard sale ?---Dealer or private.----Did you hear the motor run ?-----Perhaps your motor was pieced together.-----Any pictures of it ?---Perhaps the wrong control box ?