Mercury 150 carburetor model will not idle

[cajun329]

Recently returned from rough seas, when returning to idle boat died. It would not start after. Changed external fuel filter. Now boat will start with max throttle, but dies when going back to idle. Top 2 and bottom 2 plugs are wet and black when removed. Middle 2 plugs are bone dry and medium brown. Have tried carb cleaner in all 6 carbs while running and shutdown. Drained all 6 carbs with no substantial residue. No water are particulate in external fuel filter lower glass. Looking for ideas.

 

[procraftguy]

Stuck float in carb i have had one get stuck and wouldn't fill good place to start

 

[cajun329]

update: i can idle the engine down to 1200 rpm by maneuvering the butterflies on the carbs to maintain that rpm. Any lower and it stalls. Unhooked the common arm and maneuvering the butterflies on the top two or bottom two stalls engine, must maneuver middle two carb butterflies to keep running in the 1200-1500 rpm range.

 

[Chris1956]

You might tell us the year of the motor. It sounds like a an inline six, except for the number of carbs.

BTW - spraying carb cleaner into the carb throats does nothing to clean them. The carb cleaner must be sprayed thru the jets and passages inside the carb, to be effective.

 

[cajun329]

This is a 2001 merc 150. the 3 carb bodies that each feed 2 cylinders. If I hold throttle at 1200 rpm it runs less than that it dies. pulled each jet on each carb and cleaned (15) with no success. Guess next step is pull carbs and clean. My life since ethanol gas has sucked.

 

[Chris1956]

Yes, sounds like cleaning the carbs is next, followed by a link and synch. Make sure the carb throttle plates are synched with each other and the timing.