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no spark

Robert, I'm not an expert, but I have experienced the same thing with my 1972 Mercury. Mine is much older than yours and has never had any parts upgraded or replaced. So I went through my electrical system and started replacing parts. I am sure you will not have to do everything I did. But in doing what I did, I discovered the problem was in the Cdi/coils switch box. Here is what I would suggest you do. Attach a multimeter to the positive and negative wires on your starter. Then crank the motor and note how much voltage drop you are getting. Then attach your multimeter wires to the white positive wire on your switch box and on a good ground. When you turn the key on your control box you should have the same voltage as your battery. When you crank the motor your voltage drop should show a voltage well above 9.5 volts. On my motor it will not create a spark if the voltage drops that far. If you voltage drop is significant, I would look at the starter possibly being the cause or your loss of spark, or your switch box is in need of replacement. Again, I am not an expert and if anyone of the experts on this forum has a suggestion, follow what they say first. Good luck.
 
If your motor will crank, then you electrical connections are probably ok. If you can't crank the motor try checking battery connections to make sure everything is tight.
 
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