Re: 1978 1150 mercury
Possibly your motor is not firing on all cylinder's?
Welcome to iboats.
Get a cheap timing light and use it to verify the spark on each cylinder.
That would be my first step....... then check the carbs. Those carbs must be synchronized and working properly. If a carb is not working right you could lean out and destroy a cylinder or two.
Third I would purchase a good shop manual.
JUST FYI a 6 cylinder motor will run and rev up with just 2 cylinder's and still "sound fine" to the human ear.
