Johnson 175 94' full throttle

[cayman]

The engine seems to run fine up to 85% throttle and when you go to full throttle, the engine sound bogs down and sounds heavy. There is also no increase in speed or RPM. The bottom-port cylinder plug fouls but most things have been checked - plugs, wires, coil and carb. ?

 

[JB]

Re: Johnson 175 94' full throttle

Could be many things, Cayman.<br /><br />Please give us more detail. Rpm? What else did you find other than the dirty plug?<br /><br />Have you done a compression check? Have you verified that it is running on all 6? Have you verified the link 'n' synch adjustments?<br /><br />Let us know.

 

[cayman]

Re: Johnson 175 94' full throttle

RPM gets to 4800, I am doing a compression check soon. I haven't come across the link and synch adjust. Tell more.

 

[cayman]

Re: Johnson 175 94' full throttle

The other 5 cylinders seem to be firing well.

 

[JB]

Re: Johnson 175 94' full throttle

Hi, Cayman.<br /><br />To verify that all cylinders are making power, disable each spark plug at idle. If rpm drops, good. If not, that cylinder is dead.<br /><br />The link 'n' synch adjustments are detailed in the Repair Manual. It synchronizes all of the carbs and sets the ignition timing advance linkage from carbs to stator.<br /><br />I suspect that your bottom port cylinder is broke, either compression or fuel mix problem.<br /><br />Good luck.