Motor bogging down past half throttle

[tbordofske]

1984 Mercury 150 magnum 16' Champion has no power past half throttle. Had in shop last 2 weeks. Replaced 1,3,5 switch box for no spark on 1,5. Plugs 1,5 were still clean after running. They said 1,5 were washing out and needed to adjust floats. Checked floats again. Were fine. Took to lake yesterday to test. Was able to get on a plane by getting all weight on front of boat. Once boat got on plane was able to trim out and get up to 50mph but was still missing pretty bad. At one point running wide open, motor completely lost power. Was able to start again but still had no power gain past half throttle. Checked 1,5 plugs after lake trip yestereday and now show signs of carbon buildup. I have new plugs, broke all carbs down and cleaned, new inner switch box. Any additional advice would be greatly appreciated.

 

[Solittle]

Re: Motor bogging down past half throttle

My guess that the problem is still with the carbs. Check out:<br /><br /> http://www.outboardrepairs.com/carburetors/

 

[Mod2]

Re: Motor bogging down past half throttle

Moving to Mercury/Mariner forum.

 

[greasemonkeyozi]

Re: Motor bogging down past half throttle

My guess is your jet adjustment screw is not set right...

 

[tbordofske]

Re: Motor bogging down past half throttle

Took it back out to lake and tested today. Was able to come out of hole better but the top end was still rough. Never got full thrust. Would act as like it was missing. Where is the jet adj screw? What part of the carburators could be not right? When removed they were spotless.

 

[tbordofske]

Re: Motor bogging down past half throttle

Took boat to another dealer. Ran compression and leak down test. Found there were only 2 cylinders any good. Compression ranged from 92-110. Looks like a total rebuild. Any recommendations on doing rebuild or trying to part out motor and sell boat?