The importance of a clean IAC

My boat has been sitting at the house for about 7 weeks and I've not yet got round to winterising it (we went away for some fun in the sun!) so today I moved it into the barn and ran the [2007] 225 in a large tank (a 1000L IBC with the top chopped off) of fresh water to give it a flush.

Everything was fine although after about 10 minutes of idling I noticed the old fluctuation of RPM that I've noticed since we got the engine.

Just for kicks I pulled the IAC and sure enough the mesh was a bit cruddy and black so I shot carb cleaner into it and gave it a good shake. Satisfyingly black fluid came out when I emptied it so I did it again, blew it out with the air line and fitted it back onto the 225.
I fired it back up and immediately the rpm fluctuation was gone at idle and remained that way for a further 10 minutes until I shut it down again.

The moral of this story is to regularly pull the IAC and give it a clean!

(I cleaned the IAC mesh last winter but didn't really have a go at cleaning out the inside of the valve which I presume you need to do - I may even do it again before I put her to bed for the winter!)

Thanks for that metal chick - will be adding it to the list!

Metal-chicken - good advice. I clean mine sporadically. Screen seems always dirty when I do.

I've noticed this surge in idle RPM. What is the IAC and how do I clean it?
Thanks

Can anyone explain what the heck an IAC is, what it does, where it is, and how to clean it?
Thanks

It's attached to the throttle body on the top of the engine....Part number 15 here: https://cdn.boats.net/MTA/d/b/NjQzMTk-b1beacbe.png

IAC = Idle Air Control (AFAIA it controls the amount of air at idle)

Simple to clean, just unclip the cables and remove the two bolts. Squirt liberally with carb cleaner and remove the black gunkiness from both inside and on the wire mesh.

Thank you for the detail. I thought that gizmo was the IAC but didn't want to play with it. I noticed the low RPM surge before I put it away. I'll put the IAC cleaning on the list. Thanks.

While your at it, also clean the flame arrester screen - item #6 in that graphic. They can get gummed up. Not sure what the consequences are if they do, but I like to keep things in that area as clean as I can,.

Yes clean IAC works wonders.My engine used to fire up (after prolonged time unused) and die.
On the second crank it would fire up for good but since I cleaned the IAC it fires up on the first crank every time.