How to clean IAC of 4-stroke Yamaha Outboard

[melaatik]

Any tips how to do it step by step would be very helpful. Especially in which extend the valve assembly should be opened and what stuff to use in cleaning?

IAC valve = idle air control valve

[rodbolt17]

I use combustion chamber cleaner and air.
doesn't always work.
why do you think yours needs cleaning?

[melaatik]

The idle in neutral fluctuates after slowing down from higher rpms. I think the reason might be stucking IAC valve.

Have you opened two torx screws in the IAC assembly when making the cleaning? Is the assembly difficult to re-assemble?

I think I will use crc air sensor cleaner

[rodbolt17]

dunno.
I spray them out and blow them dry with combustion chamber cleaner.
if the still wont work properly or get over 200*F after several cycles with the laptop I deep six them and replace it.

the ECU does NOT monitor the physical position of the ISC.
that ISC controls idle speed.
if it mechanically sticks the ECU will constantly toggle it trying to make the idle stabilize.
eventually it will overheat, then overcurrent the ECU taking out the ECU.

as I cannot buy just the ISC I have no reason to disassemble them.

[melaatik]

If the valve is NOT serviceable (protected by two tamper torx screws), I think the valve CANNOT be cleaned properly because the sliding valve is INSIDE the plastic housing of the assembly. I can only see part of the sliding valve that can mechanically stick. See figure below showing one torx screw.

WP_000974.jpg

I heard that cleaning of IAC should be done reqularly to avoid idle related problems, but how to do it properly would be nice to know.

[TownsendsFJR1300]

You don't have anything to lose at this point if its acting up and it doesn't clean up and behave as Rodbolt suggested.

You can get the security torx bits and pull it apart.

Somebody assembled it, can't be too hard to dis-assemble. There's likely a spring in there so I would go slow separating the halfs... You should be able to feel, after cleaning and re-assembly if the unit moves any easier. Thats besides seeing if theres any crap inside it, dry, sticking, etc..

Please post if you pull it apart and maybe a pic or two.. Just curious..

[melaatik]

I wont open it

Thanks for the comments.

I think I wont open the halfs at this point and just try to clean the assembly as it is in fig. This because basically the engine is working ok (but not perfectly) so I don´t want to take the risk of breaking the valve. Also Im not sure if the real reason for idle fluctuating is in this valve or not. I don´t have laptop diagnostic to check for any other codes/reasons.

Do you have any experience can there be another part not working perfectly and causing idle problems after slowing down from high rpms?

[TownsendsFJR1300]

Not specifically however, Yamaha makes a product called "Ringfree" (it isn't cheap but works very well).

It goes in the fuel and cleans the fuel system, injectors, rings, top end, etc. If you have a little bit of crap/varnish, etc, in the system, that may very well help.

I run it 100% of the time with non ethonol fuel and K100. The engine runs better now than when new.

In either case, its good preventive maintanance, will help clean up the important internals as well.


I think it may have been mentioned in another thread, but did you re-set/check all the linkages connecting the carb/TB linkages? One slightly off will have that cylinder working harder, or less than the others.

[melaatik]

injection no carbs

My engine is F100 -06 EFI. I also use non ethanol fuel only but havent used any additives yet.

I also bought STP fuel injection cleaner but I don´t think it will give any help. Also Im uncertain if its suitable for Yamaha Outboards at all. So havent tried it yet.

[melaatik]

You don't have anything to lose at this point if its acting up and it doesn't clean up and behave as Rodbolt suggested.

You can get the security torx bits and pull it apart.

Somebody assembled it, can't be too hard to dis-assemble. There's likely a spring in there so I would go slow separating the halfs... You should be able to feel, after cleaning and re-assembly if the unit moves any easier. Thats besides seeing if theres any crap inside it, dry, sticking, etc..

Please post if you pull it apart and maybe a pic or two.. Just curious..

Is it okay to try to move the sliding piston of the valve? I mean that isn't it sensitive for touching? Should the piston move against spring force?

[rodbolt17]

its a simple stepper motor.
as the motor turns it threads the pintle in or out to allow more or less air to pass.
its also rather expensive from Yamaha.

fuel does NOT pass the valve ONLY air.

I explained how I would clean and test it.

[TownsendsFJR1300]

Is it okay to try to move the sliding piston of the valve? I mean that isn't it sensitive for touching? Should the piston move against spring force?

I don't know. I suspect it would be but don't have any experiance with it.

If it was mine, I'd clean it as posted above.


If it still acted up, I'd pull it apart, check, clean, etc the internals. I've pulled switches apart that had folded over tabs, edges, rivited, etc, NOT designed to come apart to check the internals.

Two tamper proof torx screws make disassembly pretty easy to do ..Just need the special bits which are easily purchased. I bought mine from Amazon for under $10.00. Already used them on a DVR with tamper proof torx screws.. Someone put it together, it can come apart...

[melaatik]

IAC feels very warm after running

Today I got some ride and after that I checked the temperature of IAC valve. It was noticeable warm, and much warmer than the surrounding parts. I was not able to touch very long without burning my fingers, so the temperature was about 50-80degC.

Is this normal or should I order new IAC?
Its relatively expensive component so I would like to be quite sure about this before ordering it. Thanks.

[bbakernbay]

How does the IAC get hot.

I have a Yamaha F60 outboard that is very difficult and sometimes impossible to start after only 10 minutes of half throttle running.

Leave it 10 minutes and no problem.

[99yam40]

this is an old thread. probably better if you start your own with all info.

if IAC is stuck the ECU keeps trying to move it and it overheats from the constant current pulses hitting it.

also check your water flow thru your fuel cooler