1998 Mercury 150 high idle after running

[T.Rhoten]

I just did a carb rebuild on my Mercury 150 v6 (3 carbs). Completely stripped them , Soaked in clean over night, Sprayed with air compressor and more carb cleaner. Put carbs back on and had a high idle around 1200rpm. Pulled carbs off check float levels and they were good. I did notice that one of the butterflies were slightly open. adjusted the butterfly back to normal and reinstalled carbs. Idle went down to about 700 rpm. I did put the mixture screws back to the same 1 1/2 turns I pulled them off as. Ran the boat on the river 2 times now. Runs perfect for the first hour or two or wakeboarding then the idle wants to just back up. Making it rough going in and out of gear. Boat never did this until the carb rebuild so im looking somewhere in there before I pull them back off for the 3rd time. Maybe mess with mixture screws before pulling them off again? The linkage is not getting caught up in anyway that I can see. Maybe adjustment on throttle cable or linkage between carbs? There is only one roller that stops the linkage of the carbs and it is on the bottom carb. Is the bottom linkage suposto be sitting on the roller? I will have some pictures to upload tomorrow.

 

[DavidMoore]

Sounds like a lync and sync problem. Yes the roller should be slightly touching the roller.
Follow the steps in the attached document and see if the situation improves.

 

[Dukedog]

Yes the roller should be slightly touching the roller.
.

not ta say that's not tha right but we've found that a very tiny gap, even paper thin, will make sure that it stays completely on tha carbs "idle" circuit without any influence from any "linkage" adjustment...this also limits any idle issue to either carbs or idle timing.. some folks "jus touching" gets a little heavy handed... jus something we've learned over tha years.....jmo

 

[T.Rhoten]

Awesome , I haven't done a lync and sync on the motor since I have owned it the past 5 years. So doing one should not hurt. I did get a chance to run it today and noticed when going in and out of gear after a while the throttle cam was getting stuck very slightly forward onto the roller making the carbs open up just a bit. If I pushed the throttle cam back while In natural it would allow the roller to sit back in idle position. Maybe this could be a stretched out throttle cable that needs to be adjusted? I don't have a dial indicator so im going to pick one up tomorrow and do the sync Friday.

 

[sutor623]

You need to do a linc and sync EVERY time you remove the carbs.