50hp Johnson - 2nd cylinder has died.

[Starcraft Tony]

Here is my problem guys, I?ll try to make it short and sweet.
Motor: 1975 50hp Johnson
Problem: No spark on 2nd cylinder
History: Originally the 2nd cylinder on this motor was intermediately dropping out at random times. Sometimes after the motor warms up sometimes straight from the start. After researching the forms I decided to check the ignition coil. The coil looked bad for that cylinder as it was cracked all over the place. I pulled the spark plug wire while the engine was running and nother happened. I replaced that coil with an old one I demoed off another motor. Installed it and everything worked great for about 10min then the cylinder died again and has not come back. Thinking it was just the old coil I bought two new ones and replaced both. Still no spark on the bottom cylinder.
Again turning to the forms I?m thinking the next step would to be replace either the timer base or the stator (maybe both). Am I on the right track? Is there any tests that I can perform to verify which part is dead?

Thanks

 

[Starcraft Tony]

Re: 50hp Johnson - 2nd cylinder has died.

After a little more reading I'm thinking maybe the power pack? That is one of the more easily accessible and cheaper parts I guess I'll start there.
Anybody have any suggestions?

 

[Starcraft Tony]

Re: 50hp Johnson - 2nd cylinder has died.

"Trigger plate is cheaper then power pack".... that is for sure. Thanks for the help 6hpboat I'll run those tests after work.

 

[Starcraft Tony]

Re: 50hp Johnson - 2nd cylinder has died.

Ok, well I finally got the flywheel off. Was a little surprised at what I found. It looks as if the stator and trigger plate have already been replaced on this motor by the previous owner. I have some parts from a donor motor and they look quite different from what is currently installed (see pics)

. My next step would be to test the trigger plate wiring as 6hpboat has suggested, do I test the trigger plate wires at the powerpack (bottom two wires on the right)

or elsewhere? With how clean this stuff looks I?m thinking my problem might be at the power pack what do you guys think?

Thanks

Tony

 

[Starcraft Tony]

Re: 50hp Johnson - 2nd cylinder has died.

Anybody? Do I test wires from the trigger plate at the power pack or elsewhere?

Lets pretend that I get the 200ohm?s referenced; would replacing the power pack be the next step? So far my research hasn?t lead to a test for the power pack. I?m not very mechanically inclined so any help is greatly appreciated.

Thanks

Tony

 

[Starcraft Tony]

Re: 50hp Johnson - 2nd cylinder has died.

Well I performed the low ohm test that 6hpboat suggested and everything tested out OK. I also ran a multitude of other tests that the manual suggests and everything checks out fine. My last resort was to install an extra power pack I had laying around from a donor motor late last night, can?t wait to reinstall the flywheel assembly tonight and try to fire the ol girl up. Anybody have any suggestions as to what else I could try prior to re-assembly?

Keeping my fingers crossed.

Tony

 

[Starcraft Tony]

Re: 50hp Johnson - 2nd cylinder has died.

Success ???..for about 5 min. The motor started up pretty easy and ran good for about 5 min. then you could hear it struggle as it idled like you could hear the 2nd cylinder wanting to drop out. I?d give it a little throttle and the 2nd cylinder (and motor) would come back strong for a while. What is going on here - is this a fuel delivery problem or maybe a timing issue?

Tony

 

[oldboatsrule]

Re: 50hp Johnson - 2nd cylinder has died.

I had the exact same issue... except my top cylinder was intermittant.

When it looks like a ignition problem... suspect fuel.

When the motor starts to stumble... hit the choke.. if it starts hitting on both cylinders.. rebuild the carb.

Good luck