Whistling noise-350 MAG MPI.

[Mikes342]

Here is the link for the muffler in the throttle body.  Look at item 6.  You will find that if you install this muffler your hissing will go away.

If you go to the link above pick your engine 350 mag mpi with bravo, choose the throttle body blow up the parts schematic and look at item 6

 I hope this helps

http://www.marinepartsexpress.com/merc_sch_fs.html

Mikes342

[cwzonk]

Dale, I looked at mine I don't have the muffler that is on the parts list.  Makes me wonder what happened to it....  Sounds like we are not the only one with this problem.  have no mechanical issues don't think I am going to worry about it  to much.  The only time I really notice it is when I have the enclosure up.

[DaleM]

I slid a paper clip over the opening and it changed it's tune.  It's half in and half out of the throttle body and then I put the spark arrestor right over it.  I might look into that muffler though.  Got some 22" props coming and those may change the noise again as I will be cruising at different rpms.

Another thing is that I have engine number OL629609.  That muffler is not on the drawing for that serial engine.

Thanks again Mike.

[cwzonk]

I looked at several of the different models on the list with 350's and the ones with the muffler all had the same part # for the muffler

[alex]

my 270 f.v, powered by a 350 mag 2002, has also the same whistling noise from abt 3200 up to 3800 rpm.
The engineer told me that it is produced from the flow of the air and recommended me to turn the key in the first position 3-4 times before starting the engine, so that the fuel pump to operate.He said that if i do so this noise may disappear.I haven't tried it yet, but i wil do so  to see the results.

alex