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40EL75C Spark problems and testing driver coil

L

leogallant

Member
Anyone know how to test the driver coil with a multimeter? I know the one driver coil under the flywheel is supposed to send spark to each of the ignition coils (which I just replaced) mounted next to the cylinders. With the 2 wires that come off the driver coil, and using the multimeter set to ohms, where do I touch?

Thanks so much! I'm learning this as I go!
Leo
 
You would connect you meter leads to the two wires coming from the driver (disconnected from the external coils). Sorry, I don't know the spec. Do you have no spark? 90% of the no-spark problems are dirty, corroded, mis-adjusted breaker points. Could be the kill switch too. Try it with the kill switch wires disconnected at the coils.
 
1971 Johnson 40EL71B 40hp Outboard Motor


I have spark only on 1 plug.
I swapped the mag coil and condenser and still only have spark on 1 plug.
Anybody have this problem?
 
Did you clean the points as "fdrgator" suggests? Align the flywheel key with the fiber rubbing portion of the points... clean the points with either lacquer thinner or acetone... set them so that a .020 gauge will go through but a .022 will not.
 
Mike, you broke into a 3 year old thread concerning a different model motor. You are appreciated, but that gets confusing to us as we try to reason things out.

90% of no-spark issues are due to dirty or corroded points.

If that doesn't fix it, please start a new thread and let's start over.
 
If you swapped a coil without pulling the armature plate you need to do it all over again. disconnect both coils and test from ground wire to plug wire and ground wire to points wire both coils should be close to the same for primary (low resistance) and secondary (high resistance). To properly install a coil you must pull the plate and coil and fully install the plug wire into the coil and then slide the boot on the coil then install the coil into the plate and make sure the front of the coil laminate is flush with the boss it sits on in order to get the proper air gap to the flywheel magnet. I have had the cutout switch go bad just disconnect the small black wire from the magneto plate from the cutout switch and see if you get spark on both cylinders?
 
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