1969 85hp johnson cyl 3-4 missing

[Myboatwontgo]

ok i have an 69 85hp johnson and it missing on 3 and 4 i checked for spark it seems to be good spark but the plugs are wet , so im assuming its not a firing prob i tryed to set low idle screws but they seem to do nothing as well what could i be missing?????

 

[kenmyfam]

Re: 1969 85hp johnson cyl 3-4 missing

If you have wet plugs then it is a firing problem. You should see a really healhy fat spark when you test it out and it should be able to jump a good half inch. Sounds like it is breaking down under compression to me.
Start with the plugs and work back from there.
Lets see what the other folk think ??

 

[tashasdaddy]

Re: 1969 85hp johnson cyl 3-4 missing

check compression on all 4 and compare should be with in 10% of each other, and preferably over 100, had a '69 115hp that love to eat power packs, i every 2 years.

 

[jdupree]

Re: 1969 85hp johnson cyl 3-4 missing

I have a 1988 90hp Johnson. I had a similar problem. I had 2 cylinders that appeared to be firing but not enough to ignite the piston. Turned out to be the power pack. Have you ever replaced yours?