Guys with IAC issues tell me what you think

[Tommywalton1974 175]

I've read all these threads but none I can find seem to describe my issue. It seems similar to some.. Here goes.

 

I ran my 230 yesterday without any issue, trailered it and went home. Put it back in today and almost couldn't crank it. Volts were 100% and it just whirled away. It usually cranks within a second or two, this time it just cranked and popped a little. I raised hatch and saw what looked like fuel smoke coming from exhaust up around the platform. It smelled very rich. I went back and tried again with no luck so I have it throttle while cranking and it finally cranked. It ran rough for 10-15 seconds and all seems fine now. This is the only time it's ever done it.

 

Fuel filters both have only 85 hours on them. Distributor cap and rotor are new also. Plugs are good. The boat runs great all but this one issue.

 

Did any of you guys with IAC/IAC muffler issues experience this?

[jiriki 13]

I smelled gas when I couldn't get mine to start. It would crank forever. In order for mine to start, I had to give it about 40% gas and turn the key. It usually starts immediately. Now that I know mine is because of a clogged muffler/air filter, it makes some sense (at least in my head). The smell of gas tells me I was flooding it. Not enough air to mix with the fuel to ignite it. When I opened the throttle, I was artificially letting in air to mix and it had the right ratio to fire. That's my current theory. Any real gear heads can chime and tell me I got it wrong any time

 

I personally suggest getting that muffler out and looking at it. Probably 15 minutes to do if you've taken the air plenum off before. If you have small hands, you can remove the cooling hose and sneak in a socket, 3" extension, and wobble thingamajig and take it out. It's not easy that way. You probably saw how dirty mine came out....black..

[Bigcatpt 408]

Someone needs to put together a DIY guide to finding and replacing this IAC filter!

 

Anyone have a part number for the filter?

[jiriki 13]

Filter: http://www.marineengine.com/newparts/part_details.php?pnum=MER35-865266

 

My method required hand/wrist contortion and a bit of dexterity and basically skips removing the air plenum. The better method is below.

 

Taking off the air plenum (which I figured out how to do afterwards) is the easy way. 6 screws off the top and there screws on the side attached via bracket on each side. Once that is off, the IAC valve and manifold is clearly visible on the port side across from the exhaust riser. Take off the iac valve and manifold off the block. The filter is tiny and inside. Take the two apart. I think I used 7/16 socket.

 

Black scorpion.

Edited August 25, 2014 by jiriki

[Tommywalton1974 175]

Thanks. What kind of gasket is between the plenum/lower manifold?

[jiriki 13]

http://www.marineengine.com/parts/mercury_marine_parts/sn/0W395161/33500288S/10108_70

 

Look at #16

[Bigcatpt 408]

I just found this info for guys with the 5.0 motors (not Black Scorpion). It is from some different forum but was well written with pictures.

 

Merc MPI engine does not start, idle or is beeping twice every minute

An IAC (idle air control) is designed to adjust the engine idle RPM speed by opening and closing an air bypass passage inside the throttle body.

Pay your mechanic about $300+ to fix it for you or do it yourself and do a better job for about $100. It’s less than a one hour project the first time you do it and will leave you feeling you know your boat better.

The IAC controls the air flow at idle speed. A failed IAC causes the boat to not be able to idle. Also, smartcraft equipped boats will give a code of 2 beeps every minute for a variety of issues.

Alarms for the cooling temp, oil pressure, and drive fluid level are constant. The most common reason for the 2 beeps every minute is a bad IAC.

If you take the boat out of gear by pressing the button on the throttle at the helm and manually control the throttle and are able to start the motor and keep it going yet if you pull the throttle back to neutral the motor dies, the issue is most likely your IAC.

Change your IAC, under $100, easy DIY job.

Also change the gasket.

As long as you are at it, get a new IAC muffler filter and lets make sure the Flame Arrester / Air Filter is clean.


Parts you will need:
- IAC Vavle Idle Air Control, Mercury - Mercruiser 862998 1 $83.56
- Gasket, Mercury - Mercruiser 27-863112 1 $1.22
- Muffler Iac (filter), Mercury - Mercruiser 35-863829 3 $1.24
- Shipping ground = about $10.
- one spray can of carburetor cleaner, any brand. Wal-mart has this for about $2

Tools you will need:
- Open end wrench, size #10 metric to remove and reinstall the flame arrester / air filter
- Allen wrench set to remove and reinstall the IAC
- Small needle nose pliers to remove the old IAC muffler filter.
- 2 gallon Bucket to wash the flame arrester
- boat wash or any liquid detergent to wash the flame arrester
- hose with running water to wash the flame arrester




The above costs are from Wholesale Marine.com I am not associated with them so feel free to shop around. The costs are only to give you one example so you know what to expect.


Remove your flame arrester part #24 / air filter. To do this remove engine cover knob #28, engine cover #27, (3) stainless nuts M6 #26, cover mount bracket #25 and then the flame arrestor / air filter #24





Under the flame arrester and inside the air intake "THROTTLE BODY ASSEMBLY" part #1 is a mesh filter called a IAC muffler filter. It is shoved in a little rectangle. Pull this IAC muffler filter part #6 out then replace with new IAC muffler filter. It may look black and be hardily together if you have not changed it in a few years. You may need a small needle nose pliers to pull the old one out. Push the new one in by hand using your fingers.

On top of the engine is the IAC. It’s also under the area of your flame arrester / air filter but not inside then air intake. If this is your first time changing it, it will be painted back just like everything else. Your replacement part will most likely not be black, it will be shinny metal.


Unplug the wires at the IAC tip then remove 2 Allen wrench screws part #17, take off the old IAC part #16, make sure you have removed the gasket part #15, install the new IAC and gasket.


If you have not cleaned your flame arrester / air filter part #24 this year you may as well do this at the same time. Buy a can of carberator cleaner, about $2 at Wal-mart and with the flame arrester / air filter part #24 removed and away from your boat spray the flame arrester / air filter part #24 with carb cleaner. Use the entire can turning the flame arrester / air filter as you spray it then rinse with water, wash in soapy water in the bucket, rinse again, shake it to get it mostly dry, let it dry the rest of the way in the sun, reinstall.

Go for a test ride and let us know how it goes.

I carry a spare IAC, gasket and IAC muffler / filter.

[jiriki 13]

The muffler/filter is inside the manifold for the IAC valve. If it is clogged like mine, with the IAC wide open, in theory, the engine would be starving for air and would have trouble idling. Someone said the computer will spit out codes if the IAC valve is bad.

 

Cleaning the flame arrester sounds like a good idea.. i might do that. Considering how much black carbon was on the IAC muffler/filter, I'm guessing the flame arrester is probably not in the cleanest state either.

[chadr 328]

Is this something that is on a regularly scheduled service schedule memo somewhere? I am definitely not a mechanic so I would not have known about this unless my engine was running crappy and probably would have had to take it to the dealer for a diagnosis! How often do we all need to be changing this one out?

[Tommywalton1974 175]

http://www.marineengine.com/parts/mercury_marine_parts/sn/0W395161/33500288S/10108_70

 

Look at #16

Thanks. I will go ahead and get the gasket, filter and valve. HAve it on standby. I had the two beeps once a couple of months ago. I considered buying a scanner. This seems to be the most common reason for the beeps with occasional starting issues. Thanks again for the link

[jiriki 13]

I believe the flame arrester is on the yearly clean up list..

[Tommywalton1974 175]

I checked mine it's very very clean.

[jiriki 13]

Just took mine off.. seems pretty clean.. washed it anyways.

 

The throttle bottle behind the flame arrester is covered in oil.. is that normal?

[Tommywalton1974 175]

I'll look closer and let you know what mine looks like. Have you had any cranking issues after replacing the muffler??

[jiriki 13]

none so far

[Bigcatpt 408]

I pulled off my air cleaner/flame arrester last night. It was filthy!!!! I cleaned it up with some carb cleaner and then soap and water.

 

Also pulled out my IAC filter. It too was filthy. I can not find anyone locally around here that has one in stock. So I am going to try and clean it and reinstall until someone can get one here on order.

[jiriki 13]

How dirty is the throttle body itself? The flat metal valve. Mine has grease on both sides.

[surf moocher 127]

I pulled off my air cleaner/flame arrester last night. It was filthy!!!! I cleaned it up with some carb cleaner and then soap and water.

 

Also pulled out my IAC filter. It too was filthy. I can not find anyone locally around here that has one in stock. So I am going to try and clean it and reinstall until someone can get one here on order.

 

My mechanic just cleaned it out and put it back in when he was working on my boat.

[Bigcatpt 408]

How dirty is the throttle body itself? The flat metal valve. Mine has grease on both sides.

Mine is pretty dirty. I plan on getting in there with a toothbrush and a little carb cleaner and getting some of the gunk off the sides and the butterfly valve.

[Bigcatpt 408]

My mechanic just cleaned it out and put it back in when he was working on my boat.

I plan on doing just that since I can not find one locally. I have one on order but it won't be here til next week.

 

The filter really looks pretty fragile though. I am afraid that when I put carb cleaner on it that it may just disintegrate into nothing.