35hp Johnson Idels Rough

[darylf08]

I have a 1984 35hp Johnson that runs fine at fast idel or more ( out of water on muffs). At a slow idel it runs rough, jerks like timeing or not enough fuel. Also the motor fouls out plugs 2 to 3 times a year. I can only run the boat at a no wake all the time with the lake rules I live on. So I run the motor about 75:1 mix.
Looking for Ideas on what to check ? Thank You

 

[bktheking]

Re: 35hp Johnson Idels Rough

Have you cleaned the carb?

 

[darylf08]

Re: 35hp Johnson Idels Rough

Carb is rebuilt

 

[bktheking]

Re: 35hp Johnson Idels Rough

Then it could be something stuck in the reeds, reed shifted, broken. Any fuel coming out of the carb?

 

[darylf08]

Re: 35hp Johnson Idels Rough

I don't remember seeing any excess fuel from carb, I will take closer look tonight. Is there anything else I can look at?

 

[1946Zephyr]

Re: 35hp Johnson Idels Rough

I would do what BK's signature says: Check the compression uneven compression will cause a rough idle. If you're running 75:1 mix, you're ruining your motor and may have possibly scored a piston bad enough to make the rings stick in a grove. Your motor was built close to the time when OMC thought they could manufacture a motor to run on 100:1. Well, as a result, they had a big recall and a lot of customers got free rebuilds.

You should be running at 50:1 even though you are running in a no wake zone. Gap your plugs at .040 to prevent fouling.