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1977 mercury 850 positive ground?

A

adamandtater

New member
i just picked up a 77 merc 850, problem i am having is that the motor seems to have positve juice running through the block causing the coils to spark on the outsides and in the dark it looks like the 4th. i dont see where i could be grounding out a hot wire.. any help on this i would appreciate

thanks adam
 
Check all your grounds and especially on the ignition plate that coils are mounted to. Its not unusal to to see the ionization of the surrounding air around a coil.
 
ok thank you that cured the fireworks display, now heres the next problem. i have spark on 3 and 4 , now with the switchbox hooked up to all 4 coils. when i remove the green wire to coil 1 positve i gain spark to 2, 3, and 4 coil. the top 2 coils are new. i also got a used switchbox off ebay and when i hook that one up i get spark to coils 1 and 2 but not 3 and 4. i moved stator wires and have the same result. my stator is putting out like 6600 ohms (6.6k) across the red wires and 66 ohm across the blue wires. trigger is new also, engine had some really bad wires and ive fixed them the best i can without replacing everything.
 
I hate to say this, but if you hooked the battery up backwards (positive ground) your switch box is toast. Had this exact thing happen to one of my customers.

Jeff
 
well thanks everybody, i dont want to blow another switchbox should i replace stator and switch box at same time? what is the primary cause that makes switchboxs bad besides reversing battery cables?
 
Test the stator for continuity,heat it with a hair-dryer,and test again.If you still have continuity,stator is good.This is just in case there may be a fault in the stator that would open when it heats up.On these motors the stator just trickle charges the battery.
 
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