help locating Idle air control valve

JWGuns

Recruit
Joined
Oct 17, 2014
Messages
5
hi everyone, long time reader of the forum here but first time posting. I have been troubleshooting a rough idle and stalling problem on my 1990 40 hp johnson outboard. I do have a service manual and have been going through many possible causes as the manual calls for them in addition to checking out the input of other posts regarding this issue here on the forum. Currently I am trying to locate the Idle air control valve so that I can test it. I feel like a bonehead posting such a simple question but even with the service manual pictures and description I have been unable to find the dang thing! my engine model number is J40TELESR. im stumped! please help!
 

Bosunsmate

Admiral
Joined
Apr 7, 2012
Messages
6,129
Its the screw which has a flat screwdriver head and is on a 45deg angle on the starboard side of the carb near the top, towards the back of the carb.
If that doesnt fix it you might need to get a can of carb cleaner and blast it down every tiny tiny hole until they are clear
 

JWGuns

Recruit
Joined
Oct 17, 2014
Messages
5
i think you are referring to the "slow speed screws" on my carburetors is that correct? the service manual states the idle air control valve is actually a component of the electrical system and is somehow integrated inline after the fuel pump but before the carburetor(s) which is why im confused. maybe my model does not use actual automatic valve which would explain why i cant find it.
 

Faztbullet

Supreme Mariner
Joined
Mar 2, 2008
Messages
15,589
IAC valves on 4 stroke outboards not 2 strokes...thats why you cant find it.
 

Bosunsmate

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Apr 7, 2012
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6,129
Not sure why it keeps sporadically posting my first response, timing must be out.
You could try backing that screw out a bit and also spraying carb cleaner down all the jets
 

racerone

Supreme Mariner
Joined
Dec 28, 2013
Messages
36,047
What brand of manual is telling you about this " air control valve " on your 1990 model 2 stroke ?
 

Fun Times

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May 16, 2009
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8,776
Not sure why it keeps sporadically posting my first response, timing must be out.
It's really nothing you did per se. but if you had an error code pop up while posting, a quick freeze up during posting and/or kept clicking on Post Reply trying to get it to post then that could be the reason you and many others may see multiple posts or topics even hours later. It has more to do with forum issues since doing forum software changes that's taking longer than preferred to repair.

If you or anyone runs across multiple posts inside a topic like this, please feel free to click on the Flag post icon to let someone know to come in and delete them, it would be appreciated. Thank you.:)
 

JWGuns

Recruit
Joined
Oct 17, 2014
Messages
5
Hey everyone, thanks very much for the replies, there definitely isnt an IAC valve on my 2 stroke. i must have been staring at the manual too long when attempting to figure this out. none the less, thanks for entertaining my question! The rebuild kit for my second carb should be here tomorrow and im hopeing that the rebuilds and retuning will solve the issue. One thing that i noticed when rebuilding the first one was the size of the hole in the main jet that the float needle plugs up when it rises. the hole in the old jet was worn to nearly double the size of the new jet! (ok maybe thats an exxageration) but it was noticeably larger. im thinking that the main jets werent being plugged and at low rpm the engine was just being flooded.
 

daselbee

Commander
Joined
Jan 20, 2009
Messages
2,765
Better think again.....
The "main jet" you are describing is not the main jet at all. You are describing the fuel inlet needle and seat.
It is merely a valve that allows fuel into the bowl as it is consumed by the engine.

Main jet is located in the bottom of the carb bowl, usually buried behind the carb bowl drain screw.

You need to trash that Clymer or Seloc manual and get an original OMC factory manual for your motor.
 
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