76 20 HP JOHNSON NO SPARK

[AEROCOOK]

Looking for some help in diagnosing an electrical problem with my 20 hp Johnson (1976).
On Saturday I was going across the lake at WOT when the ignition cut out completely and instantly. The first thing I checked for was spark, and concluded that there wasnt any. I disconected the kill switch to se if it had any effect and still no spark. The only testing I have performed was a pin test to confirm that the kill switch is working (it is) and I then pin checked the 2 connectors that the kill switch wires go to and found continuity where I dont believe there should be any???
Any ideas or tips on what to check next?

 

[boatingbob]

Re: 76 20 HP JOHNSON NO SPARK

Looking for some help in diagnosing an electrical problem with my 20 hp Johnson (1976).
On Saturday I was going across the lake at WOT when the ignition cut out completely and instantly. The first thing I checked for was spark, and concluded that there wasnt any. I disconected the kill switch to se if it had any effect and still no spark. The only testing I have performed was a pin test to confirm that the kill switch is working (it is) and I then pin checked the 2 connectors that the kill switch wires go to and found continuity where I dont believe there should be any???
Any ideas or tips on what to check next?

No spark to either plug? if both kill wires are grounded out that would cause your problem. Check the wires nder the hood. If you have ground issues that could be it, otherwise check for ignition system failure. Just to make sure try new spark plugs first. Not common but better to rule that out before pulling things apart.

 

[Xcusme]

Re: 76 20 HP JOHNSON NO SPARK

Pull the flywheel and have a peek at the crank keyway.....

 

[AEROCOOK]

Re: 76 20 HP JOHNSON NO SPARK

Thank you for the replys.
I took the flywheel off and inspected the wiring and keyway / cam and it all looks good. Unfortunately my Seloc manual is vague to say the least when it comes do diagnosing ignition related issues, in fact they dont even recognize the existance of a 1976 Johnson 20 hp. Im beginning to suspect the driver coil and I have a buddy thats a wizard at this kind of thing, but he would at least like a wiring diagram for the motor in order to get started, any idea where I might find one?
BTW even the local Johnson dealer and OMC dont list this model (20BA76)...Whats up with that?

 

[F_R]

Re: 76 20 HP JOHNSON NO SPARK

How did you establish that it's a '76? They don't even show as having made a 20 in '76. Could it be a commercial motor or made-in-some-other-country model?

 

[AEROCOOK]

Re: 76 20 HP JOHNSON NO SPARK

Both are excellent questions that I have been trying to answer for a while now.
I can tell you for sure that the model number is 20BA76D and on the same tag as the model # / serial# it says Outboard Marine Corporation Peterboro Canada. I have to believe that the model was intended for the Canadian market given that it has the Canadian designation on the tag, but I could be wrong. Also worth mentioning, I use the boat on a small lake here in Ontario, and there is another identical motor on the same lake, so they must have been available.

 

[F_R]

Re: 76 20 HP JOHNSON NO SPARK

Shows what I know. I thought Canadian and US models were all the same. Anyway, for whatever it is worth, there is a parts list and breakdown on Bombardier's site http://epc.brp.com/default.aspx?brands=ej&lang=E
But they still don't show that model or a 20hp. Probably very similar to the 25 though (I guess).

 

[AEROCOOK]

Re: 76 20 HP JOHNSON NO SPARK

Well my buddy came over and ran a pile of tests on the motor, shook his head and said "I cant see anything wrong". We then re assembled the motor, pulled the cord and voila, lots of spark! I know for certain that when the motor died on the lake there was no spark, and because both cylinders quit at the same time, we believe that the driver coil which provides power to both external coils is the likely culprit. This brings me to my next question is...Is it possible or common for a driver coil to fail when hot and then work again when it cools down?