1983 Mercury 115 hp Tower of Power 2700 RPM

[Snowballak22]

I have a 1983 Mercury 115 hp Tower of Power and it will not rev past 2700 RPM. It is a little hard starting but once it has warmed up it starts every time. At the exact throttle position it runs great at 2700 rpm, a hair past that point it starts to surge like its trying to go faster but can't. There is no sign of misfire at any time.

 

[Texasmark]

My first guess is a link and sync, checking for a worn cam that operates the butterflies, or worn linkage rod hardware.

 

[Snowballak22]

I also forgot to mention that it has an average of 115# compression

 

[CV16]

I'd clean the carbs.

 

[Snowballak22]

Thank you for the quick response. I gave had the carbs cleaned and Lynx and sink preformed by a certified Mercury Mechanic last week. The test run after this is when I found out about the 2700 rpm issue. I talked to him this morning and he said that it's the high rev limiter that is not working? Is this the Stator or Trigger Plate that controls the high or low rev limit? Or could it be the Switch Box. Any help would be appreciated, I'm new to this outboard stuff.

 

[Texasmark]

On later engines, like late '90's everything is modularized and the ORL is a separate module allowing you to pull the plug on it if it is suspect. Also on later engines, the regulator/rectifier module has a gray wire that sends rectified sinewaves to the tach to operate it. That grey wire Ys and goes to the ORR module too. Maybe you can adapt that to your switch box. A schemtic would help. I don't know if or when Merc changed color codes.

 

[Chris1956]

I doub't your TOP has a rev limiter. It does have a high speed stator winding. You might check that.

 

[Snowballak22]

My next question would be: Is it better to replace all of the electrical components at the same time (Stator, Switch Box, Trigger. Coils and .....) or is one at a time ok?

 

[racerone]

That would be a big $$$$ fix.---What if none of those components are bad.---Find a shop that knows how to trouble shoot these fine motors.

 

[Watermann]

Thank you for the quick response. I gave had the carbs cleaned and Lynx and sink preformed by a certified Mercury Mechanic last week. The test run after this is when I found out about the 2700 rpm issue. I talked to him this morning and he said that it's the high rev limiter that is not working? Is this the Stator or Trigger Plate that controls the high or low rev limit? Or could it be the Switch Box. Any help would be appreciated, I'm new to this outboard stuff.

Yeah that may be the problem with the stator and trigger. I wouldn't think there's a problem with all the coils and both boxes. I would work on the stator/trigger first. If you haven;t found it yet there's a great Facebook group that's only for Inline 6 Merc owners. It's a closed group. If you can make a video of the motor acting up.

Here's the FB group. https://www.facebook.com/groups/213725501742/