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Rectifier

Keeping it simple, the rectifier converts AC voltage being emitted from the stator to DC voltage which is needed in order to charge the battery.
 
I should have known that. I am trying to figure how the points get spark to start on a 40 hp evinrude 1975. I thuink from the key switch but am not getting any spark, and am trying to trace the problem.

Thanks if you can help.
 
The magneto on that engine produces the spark-----------------spark has nothing to do with 12 volts from the battery.-------------------Pull the flywheel and start with cleaning the ignition points.-------------The key switch should open the circuit on the " m " terminals when trying to start / run the motor.---------------The battery only cranks the starter and DOES NOT FEED 12 VOLTS anywhere to produce spark for the plugs.
 
Explain in detail how you set the points.--------Are they perfectly clean?--------------What gap did you set them at?
 
Explaining the ignition system takes some doing and can be done if necessary but first.........

You're stating that the engine DID run, then you set the points, and now it DOES NOT run. Reset the points as follows and let us know if this corrects the problem.

(Point Setting Of Magneto Models)
(J. Reeves)

Set the points as follows. Have the flywheel key aligned with the fiber rubber portion of the ignition points. Adjust the gap so that a .020 gauge will pass thru but a .022 will not. Should there be any question of the points being dirty (touching the contact with your finger would cause them to be dirty), clean them with a small brush and acetone or lacquer thinner.

NOTE: Should the operating cam have a small portion on it with the word "SET" imprinted, align this portion with the fiber rubbing portion instead of the flywheel key.
 
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Removed the flywheel the aligned the lobe on the cam to each point and set at .20. Replaced the flywheel making sure the key was aligned and no spark since. We did remove the flywheel and check gap and it was still good. Still no spark. Is it possible that the key switch (which I think when it goes into the off position shorts the points and kills the motor) is at fault. The wires to the switch are rough.
 
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