1977 50 H.P. Johnson Ignition Issues

[banchigu]

Hello Everyone:

I have a 1977 Johnson 50 H.P. that runs like a banshee, however in the summer months after I run it a while or turn it off and on three or four times in a row it will then not start. Now if I turn the key on and use the pull rope it will start ASAP andif I leave the key on and use a wire to jump the solenoid it will fore right up. I have changed the solenoid, the starter, ignitoin switch, and removed the old plastic coating on the red plug igniton wires and check them inch buy inch and it still does it.

As I said in the winter it is fine, once the temps hit 90F it will do it, now if I let it sit for 20-30 minutes without the cowl it will start, with the cowl on 40 maybe 50 minutes. However it will start ASAP via pull rope or jump wire on the solenoid.

Best to all of you

 

[F_R]

Nobody can sit here and tell you what is wrong with it. The only way to diagnose it is to check the circuit voltages while it is acting up. That is done with a simple multimeter (voltmeter).

BTW, how much did you spend on those parts you didn't need?

 

[banchigu]

I took them off the extra engines I have in my back yard that I find on boats that are abandoned on empty city lots. I fully understand I will try a voltmeter next time it stalls on the lake thanks for your insight.

 

[jimmbo]

You might want to verify the year, there was no 50hp in 77. It might have some consequences regarding some parts

 

[banchigu]

Jimmbo, I think you are correct it is a 50ESL74M, it is a 1974, I do not know why I said 1977.

 

[Rustywrench]

Is the main battery ground attached to the exhaust side cover? There is a ground strap that should hook in that same position & go over to the block. Ties the ground into a main ground source. When the motor arms up it is possible to lose the ground off the exhaust side covers. That is why the ground was moved to the crankcase later. Just a guess, but better to trouble-shoot it out like others have said.