75 Johnson 70hp dead cylinder

[chopper_man]

Hi,i have a strange problem going on here,my top and middle cylinders are firing and the bottom intermittently fires when it wants too what causes this????I have replaced all 3 plugs and properly gapped,replaced all 3 coils.Sometimes i will be cruising along at at half throttle then when i punch the throttle it lags in power for abit then it will kick in and go to plane right away.Please help lol!!!Has me stumped i am leaning towards that it could be the power pack maybe ???<br />Thanks in advance .Also the bottom plug is clean like new still compared to the others.

 

[JB]

Re: 75 Johnson 70hp dead cylinder

Bottom carb is malfunctioning, chopper.<br /><br />Confirm by squirting a bit of premix into the bottom carb while it is malfunctioning.<br /><br />Might as well overhaul all three, but get a manual first.<br /><br />Good luck,

 

[chopper_man]

Re: 75 Johnson 70hp dead cylinder

Thanks so much JB i just went out tried what you suggested and that's what it was.One question is it a very big job to overhaul them????