73 Johnson Seahorse 20HP No start/Spark

[FishinKaz]

Hi fellow boaters! New to these forums, great place for sure. OK I am a bit new to playing with outboards, but I have a vast mechanical knowledge in both 4 and 2 strokes in both cars and recreational toys.

Anyhow. I have completed an in depth search of the forums to get some answers, but nothing very concrete.

1973 Johnson Seahorse 20HP Model # J20CRCSA

Engine was running great so far this season, had a new pump installed over the winter season. Last weekend we were out in the boat with no issues at all. This past weekend we ventured out and the engine started very briefly then died. I was playing with it today and noticed a oily sludge coming from the pump holes, not a lot of it, but some. I also notice a bad smell of fuel, so I checked the plugs..soaked, then checked for spark. No spark at all. So I checked all connection which are ok, and all grounds. So I am hoping someone else may have come across the same issue. Neither coil had spark so I am guessing it is further into the electrical. Any help is greatly appreciated indeed.

Thanks
Kaz

 

[FishinKaz]

Re: 73 Johnson Seahorse 20HP No start/Spark

Oh I forgot to mention is has great and very equal compression on both cylinders too.

 

[14ftgrumman]

Re: 73 Johnson Seahorse 20HP No start/Spark

If it's got gas, spark and compression, it's gotta run. You got 2 out of three. Check your kill switch. Very unusual for the coils to go bad at once.
I've got 2 of these (1 20HP and 1 25HP). very dependable.
Would not be a bad idea to rebuild carb and install new plugs after the problem has been fixed.

 

[FishinKaz]

Re: 73 Johnson Seahorse 20HP No start/Spark

It has been a great engine for sure, I looked at the kill switch and it is rather basic, I removed the boot on the switch which would keep it from making contact, and it was very clean (the contacts). I agree very unlikely for both coils to go at the exact same time, that is why I am thinking is if further up the electrical system. Now these engine have another control box on the opposite side of the coils, it is wire to the coils harness is this a control box for the coils?

Thanks for the reply

 

[14ftgrumman]

Re: 73 Johnson Seahorse 20HP No start/Spark

I've fot 2 72"s. a 20 and a 25 HP.They have 1 coil for each cyl, triggered by magnets in the flywheel. You best be looking under the flywheel for your prob. Maybe magnet missing? Kill switch wires worn thru and grounded? If there is one coil under the flywheel, maybe you have found the culprit. See if it's cracked or discolored.