'72 Johnson electrical; A fine line between troubleshooting and replacing everything

[scipper77]

I have been working on a 72 9.5 and I have zero spark. The stop circuit is completely corroded on the button side of the connector. I am trying to sort this out rather than replace everything blindly. Everything appears as if it was updated within the last 5 years or so.

Question 1: If I unplug the stop switch should I be able to get a spark at the plugs?? (I'd like to fix the no spark issue without fixing the stop circuit first)

Question 2: Is it useful to remove the coil from the wire and check continuity through the wires as a check of the wires? (They show no signs of damage otherwise)

Question 3: Should turning the flywheel by hand with the spark plugs out be enough to generate spark? Right now I am either spinning the flywheel or putting it in gear and using the prop to spin the flywheel in the proper direction.

Question 4: Should it matter that for testing I am spinning the flywheel without putting the nut that holds it down back on?

 

[nwcove]

Re: '72 Johnson electrical; A fine line between troubleshooting and replacing everyth

1: yes ( but if the kill wires are chaffed and grounding out somewhere else you will have no spark to one plug or both)
2: yes and no. i would twist the wire out of the coil test it for continuity and cut a 1/4 inch off the wire and reinstall . test the coil while the wire is removed.
3.yes, if everything is working as it should, turning the flywheel by hand should show a spark. ( plz dont get into the habit of turning the prop to check for spark!!)
4. ive never had a problem using that method for testing purposes.
jmo's

 

[scipper77]

Re: '72 Johnson electrical; A fine line between troubleshooting and replacing everyth

I have already trimmed 1/4" off of the wires at the coils. I just didnt think to do a simple continuity check at that time.

How does one check the coils with the wires removed?
Can I disconnect the kill switch wires at the points? Seems like it woe eliminate all doubt there.

I have a feeling I just need to aggresively clean the points. If filing them gives me any spark ill likely replace them

 

[scipper77]

Re: '72 Johnson electrical; A fine line between troubleshooting and replacing everyth

This morning I sanded and then polished (fine, fine grit paper) the points. Good strong spark on both plugs. One of the plugs was not touching ground but I could hear it snapping as it bridged the gap to the frame of the motor. I tested the stop circuit and it was actually working. I got excited and hooked up a gas can. When I started priming Gas came pouring out of the one fuel line that the mice chewed. I work this afternoon so I'm hoping to have the motor running by the end of the day Saturday.

Thank you nwcove for the encouraging advice.

 

[JB]

Re: '72 Johnson electrical; A fine line between troubleshooting and replacing everyth

Good thinking, Scipper.

Part replacement is the most used, most expensive and least effective method of troubleshooting known to man.

 

[nwcove]

Re: '72 Johnson electrical; A fine line between troubleshooting and replacing everyth

good to hear you now have ignition!! just a tip......from your pic, it looks like there are a few dust bunnies on the mag plate and coils, clean things up well under the flywheel, when you get her running those bunnies have a knack for finding their way to the points!!! jmo

 

[scipper77]

Re: '72 Johnson electrical; A fine line between troubleshooting and replacing everyth

The original issue with this motor was that the magneto base plate was seized. I took that picture at the stage where I had just gotten the plate off and blew the remnants of the mouse nest that was underneath clean. If you look close you will see some PB Blaster sitting in the base plate as well. I can assure you that i have removed the coils and cleaned out underneath them. I have also used compressed air to get all stray junk out of the ignition area. I appreciate the tip however.