How to clean IAC of 4-stroke Yamaha Outboard

[TownsendsFJR1300]

Short of a head gasket and WP gaskets, the intake manifold and surrounding parts are usually sealed with just o-rings.

If you open up a parts diagram for your specific engine, it'll show what's where, o-rings, etc..


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[rejesterd]

It still will not continue to run after the first turn of the key on a cold start but always runs perfectly on the second turn. I can easily live with this minor issue.

I had this exact issue on my F50 (which is pretty much the same engine). It was the temp/pressure sensor on the intake manifold that was the problem. Yamaha calls it the "sensor assembly" in their parts lists/diagrams. It wasn't totally failing, but the cold temp readings that it was sending to the ECM were off by just enough where it would never stay running after the first startup attempt. But after a second attempt, it would always run fine.

I personally haven't replaced the ISC yet, but I have been thinking about removing it and cleaning it. I haven't done that yet, but I have removed the intake manifold before. It's not difficult and doesn't require many tools. But I don't see how you could reach/remove the ISC without also removing the intake manifold.

[bbakernbay]

I had this exact issue on my F50 (which is pretty much the same engine). It was the temp/pressure sensor on the intake manifold that was the problem. Yamaha calls it the "sensor assembly" in their parts lists/diagrams. It wasn't totally failing, but the cold temp readings that it was sending to the ECM were off by just enough where it would never stay running after the first startup attempt. But after a second attempt, it would always run fine.

I personally haven't replaced the ISC yet, but I have been thinking about removing it and cleaning it. I haven't done that yet, but I have removed the intake manifold before. It's not difficult and doesn't require many tools. But I don't see how you could reach/remove the ISC without also removing the intake manifold.

Thank you very much for posting your experience, which appears identical to mine.

Am I reading you correctly in that you did replace the “Sensor Assembly“ and that cured your issue?

Do you recall how much it was at the Yammie dealer?

I won’t tackle the IAC/ISC at this time because it may not be the issue and the Sensor Assembly looks like a very easy replacement and based on your experience it was the cause.

I have a used ISC/IAC purchased on eBay and the bottom part is just a chamber with the 2 hose connection ports. The IAC motor is in the top part which is easily removed with a security Torx screwdriver bit.

Look forward to reading your reply.

[rejesterd]

Thank you very much for posting your experience, which appears identical to mine.

Am I reading you correctly in that you did replace the “Sensor Assembly“ and that cured your issue?

Do you recall how much it was at the Yammie dealer?

I won’t tackle the IAC/ISC at this time because it may not be the issue and the Sensor Assembly looks like a very easy replacement and based on your experience it was the cause.

I have a used ISC/IAC purchased on eBay and the bottom part is just a chamber with the 2 hose connection ports. The IAC motor is in the top part which is easily removed with a security Torx screwdriver bit.

Look forward to reading your reply.

Yes, replacing the sensor assembly resolved the issue of it always stalling on the first startup attempt. The part was actually $200, so I regret not trying to just remove/clean my old one before buying the new one.

I wouldn't just blindly replace it. I've had other issues as well, some of which probably contributed to the first-start issue. I had spark plugs fouling due to clogged/sticking fuel injectors, for example. If you haven't sent the injectors in to be cleaned professionally, I would do that.

[bbakernbay]

Yes, replacing the sensor assembly resolved the issue of it always stalling on the first startup attempt. The part was actually $200, so I regret not trying to just remove/clean my old one before buying the new one.

I wouldn't just blindly replace it. I've had other issues as well, some of which probably contributed to the first-start issue. I had spark plugs fouling due to clogged/sticking fuel injectors, for example. If you haven't sent the injectors in to be cleaned professionally, I would do that.

Thanks for the prompt follow up.

I think I found the a Sensor Assembly Part # for my 2009 F60TLRH

You suggest it can be opened and cleaned, probably with carb cleaner, I will check it out. Is it easily opened?

My F60 runs beautifully on a 820 Sunchaser Pontoon boat.

When yours was malfunctioning, did you get the high rpms on first start. I did but now it usually dies on first crank and I turn off the ignition and immediately restart and it runs perfectly thereafter.

A few years ago if would be extremely difficult to restart when hot but my 2-step starting procedure seems to have cured everything.

Thanks for sharing your experience.

Brian Baker
Lake Talon, Rutherglen, Ontario, Canada

8D3DD2C7-18BA-47F1-8C83-A3FAB11C14D0.jpeg6D42C958-4107-48FC-9434-0B1E2ADF7F38.jpeg

[bbakernbay]

YamahaTechAcademy 573734B8-1DB9-4588-92E0-0992B9F62DB5.pngAD994832-FBC8-4E0B-81B5-BC0143FC4329.png
Youtube Video on Intake Air Temperature Sensor indicates it to be an electrical component and to me it would seem to be unserviceable but will await more experienced posters input.

[rejesterd]

I would try an electrical parts cleaner, not carb cleaner. Sometimes it's called MAF sensor cleaner at the auto parts stores. Again, I haven't done it, so I don't know if it will actually help. But if you could see the underside of the sensor shown in your pic, there would be a hole to spray into. However, that doesn't look exactly like the same one for the F50/F60.. ours has 2 mounting screws.

"When yours was malfunctioning, did you get the high rpms on first start." Not sure what you're asking, as my rpms are always higher on a cold start. It's supposed to do that when the engine is cold.

[bbakernbay]

AliExpress has them cheap for $25 46C66A36-ECD4-42C2-AC1E-004D1CA3ECCE.png
and a Japan seller has the original Yamaha part for $75 including express shipping
You are quite correct on the 2 fastening screws and D7E7A86F-2225-4344-9CEA-8C94868654F5.png

[bbakernbay]

Well I finally had the Idle Air Control Valve/Idle Speed Control Valve replaced with a used one I purchased on eBay. The mechanic at our Marina said it was about a 2 hour job as the engine manifold has to be removed.

Our pontoon boat was put back in the water a week ago after an early ice out date. The Yamaha F60 started without the crazy high speed revving that I had experienced the last 3 years but which could be easily cured by turning off the engine and immediately restart as it should.

The engine does not start on first turn of the ignition like it should but rather takes 2 or sometimes 3 turns of the ignition key so I am not 100% satisfied at this point. It seems like it is not getting sufficient fuel to ignite.

Any suggestions would be appreciated.