76 Mercury 110 no full throttle

[Rodman738]

Bought a mercury 110 a few weeks ago. Motor is excellent shape cosmetically. Had not been used for years. Checked compression which is 110 in each cylinder. Rebuilt carb and fuel pump. New fuel line.
engine starts rite up , idles well seams to run fine in test tank. When I get it on back of boat it doesn't seem to have any power. I had a older 67 merc that was having a similar issue. It was only running on 1 cylinder. I know it has spark to each cylinder but it seem s to be week with a spark checker. Does anyone have any suggestions? Coils possibly? Switch box ? Stator coils? Any advice would be appreciated!!

 

[Rodman738]

Thanks for all the feedback! I figured for a 40 year old motor someone would have ran into this problem.
Added a new set of coils did not help. Finally changed switch box ! Motor runs like it was new. I hope this will help someone else out.

 

[tacx]

Thank you for updating. Too many times posters post a question and never post the results which helps all of us diagnose issues.