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Tachometer incorrect readings

M

Mdhanners

New member
. 97 Johnson 70hp 3 cyl with vro connection.
At idle tach reads fairly well off idle bout 1100 rpm is max it will read. Also the volt meter pegs over 18v once key on engine off. Running battery voltage is apx 13.6 Key off battery volts is 12.7 normal.. I pulled the volt meter tested the Blue to ground has battery voltage the purple wire from ignition to ground has Battery voltage also. Jumped I stud to battery positive and G stud to battery negative reads over 18 volts gauge is bad. Need help not sure with the water cooled Rectifier if it's charging correctly while running if it's bad. I tried pulling Grey tack feed wire at the engine and attached to the yellow then yellow/ grey wore to Stator with engine running tach does the same thing reads 1100 rpm..
Think tach is bad but not sure. I read it can cause a fire if Rectifier is causing the problem but don't see how if the charging system is charging correctly. Like to test the Grey feed wire at tach to ground but not sure what Ac voltage reading it should have at like 1000 rpm
Please help...
Thanks
 
racerone said:
I do not believe the rectifier is water cooled on a 97 model 70 HP.
Click to expand...
I know its not the little round 3 wire typically found on Omc.
How is best way to check the input to my tach from Grey wire coming from the motor wire strip. Haven't found the specs to check what the Grey wire to ground with multimeter should read with engine running..
Hopefully you know or anyone else does..
Thanks
 
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