Throttle whistling

lifeisgreat

I have a whistling sound coming from the engine when the boat is in forward position. I’m thinking it may be related to the throttle. Could it be the iac filter? If so is it fairly easy to get to?

aero3113

Yes, it could be the filter. Especially if it’s missing. Very easy to get to. Depending on your engine it’s either in the throttle body or on top of the engine.

Willhound

I had something similar last year and it was as simple as a vacuum hose had pulled off of the throttle body probably from when I was doing some maintenance. Take the flame arrestor cover off and take a look. Also clean your flame arrestor out by soaking and light brushing with some degreaser or paint thinner or some such. But let it dry well or carefully blow it out before re-installing and starting up.

PickleRick

Do you vape or know someoene that vapes?  Smoke is a great way to find a vac leak at idle which is when a motor makes the most vacuum.

lifeisgreat

willhound-where is the vacuum hose located? Sorry for the dumb question. 

Willhound

@lifeisgreat I see from your profile and user pic that you have a 2005 270 so it should be similar but my 2000 uses the Mercruiser/GM TBI set up. If you have MPI it may vary a bit but if you look at the pic the black plastic shroud/cover over the throttle body can be removed and you'll see the throttle body with the flame arrestor (about a 6 inch across metal disc that looks like stacked wafers) which can also be removed. Be careful not to drop a nut or washer down the throttle body. My hose was on the left hand side (looking aft) and was probably for a cold start throttle advance or whatever, but just look around and make sure there's no hoses hanging. Little black rubber tube. In my pic I think it was the one at the left hand front corner of the shroud. If it is popped off you should see a nipple that it just pushes back on to. While you're at it, take that flame arrestor and clean it up. If it is partially plugged it will also whistle. Acts as a bit of a filter for larger particles from getting in your engine and also to stop flames from shooting out if you get a backfire.
Oh, and welcome to the forum! A quick user tip: if you type the @ symbol and start typing the username of someone you want to identify a pop up will show a list of user names for the forum. Click on the member name and it will place it in your text and also creates a link so that the next time that member signs on they will get a notification that you tagged them so they can see what was posted easily. For example, I would be @Willhound . Since I tagged you up at the start of this post you should see a notification up on the top left by your username.

lifeisgreat

@Willhound-thanks so much for the tip! So after reading your suggestion and some pics of other people I feel my filter is missing. I’m attaching a pic for you to see. Shouldn’t there be a filter in the throttle body? Could that be the air that I hear escaping? I checked all of the hoses and they seem to all be tight. Should I take out the flame arrestor and clean it? I see it’s a little dirty.

Dream_Inn

Yes, you are definitely missing the little filter.  Hard to say where it went, but that will solve your whistling problem.

Liberty44140

Could have been removed by the PO, could have just totally deteriorated, either way you can go to marineengine.com with your serial number and Get the right part number to make sure to order the exact one you need 

https://rinkerboats.vanillacommunities.com/discussion/8339/iac-muffler#latest

reneechris14

yup missing that filter 

Willhound

@lifeisgreat those pics are after you removed any cosmetic cover and flame arrestor, correct? If not, as in you open your hatch and that's exactly what you see, then you are definitely missing some parts. Silly question maybe, but you never know!
That plate you see that looks dirty is the throttle plate, should never need to be removed. I can't tell what that is on there, but in my opinion shouldn't be there. Maybe the engine was running rich, or had a bad spark plug or something and fuel was spitting back up through the throttle body? Mine's 20 years old and still bright brass.

YYZRC

My throttle body butterfly was dirty just like that. Cleaned it with some seafoam. 

Willhound

Hmm. What do you think causes it? 

YYZRC

Willhound said:

Hmm. What do you think causes it? 

I’m guessing a lack of preventative maintenance (cleaning the flame arrestor)?  I don’t imagine it negatively impacts airflow much but it was easy to clean so I went for it. 

lifeisgreat

@YYZRC Thanks for the tip. I will use seafoam to clean it. 

lifeisgreat

@reneechris14. I ordered the iac filter today. Thanks for the number. My mechanic said that’s the part I needed and most likely the cause of the hissing sound. 

lifeisgreat

The mechanic told me putting in the iac filter is tricky?? Is it really??

lifeisgreat

Dropped boat in water today. Boat ran then stalled about 3 minutes later. It started right back up and I was able to get it into my slip. I went and bought a fuel stabilizer today when I ordered the iac filter. Going to put it in the tank and see if that helps. Wondering if there is water in the fuel tank causing the boat to stall??  I can’t win....

aero3113

Change the fuel filters also.

lifeisgreat

@aero3113 I changed the fuel filter on the engine but do I need to change this one too? See pic. 

Willhound

Whoa! I would. Doesn't look like those fittings or filter have been touched in years.

aero3113

Yes, if you haven’t changed that in a while in needs to be replaced anyway.

aero3113

It could be your IAC also.

lifeisgreat

@Willhound @aero3113 will do thanks!

YYZRC

I found a Sierra swap for those in-line fuel filters. The merc filters were $$$ and I couldn’t swallow the cost on top of the cool fuel filters!

lifeisgreat

@reneechris14 Any special way to install the filter?

lifeisgreat

@Willhound do you know if there is a special way to install the iac filter? Thanks 

Willhound

Sorry @lifeisgreat mine is older and a little different. But I'm sure someone on here with an MPI model can comment.