Still having can't get 15hp to idle

[TownsendsFJR1300]

And is there supposed to be a gasket between the carb and the engine block? Looks like a smear of gasket goo and that’s all.

Yes, there should be a gasket there: 2006 and Later F15MSH Yamaha Outboard INTAKE Diagram and Parts

Any air leakage there WILL CAUSE a lean condition and high idle, besides damage to the engine...

Look at the parts list, see what your missing (someones been in there dinking) and get it sealed up tight again..



.

[boscoe99]

OP has a 15 Yam, not an F15 Yam.

[boscoe99]

Gotcha both.

Even if one post got deleted.

[yellowtail]

Okay. Well on my way here.
I'll order a gasket and attempt the idle issue... though I'm getting pretty good at coming into the dock at speed!!!!

Bry

[boscoe99]

Good luck getting an F15 gasket to work on a 15.

[pstephens46]

Gotcha both.

Even if one post got deleted.

Haaa. You right about that. However I might say he needs to add some goop to
it!

You gotta move fast with Boscoe and Yam on the prowl.

[panasonic]

Got my carb parts in this week and got the carb off the engine without dropping it into the water. Bonus!

I replaced the pilot adjusting screw and spring; the main nozzle and main jet; and the pilot jet. The rubber cap over the pilot jet seemed to have some kind of packing around it. Looked like a wrap of denigrating masking tape. Didn’t know what it was so just stuck the plug back in place. It felt like a firm fit.

Also couldn’t figure out how to remove the jet where the needle valve seats. So I cleaned it in place with wire and hosed it down with carb cleaner. And is there supposed to be a gasket between the carb and the engine block? Looks like a smear of gasket goo and that’s all.

Reassembled, the engine started right up. The idle is too high, but it DOES idle!!!

So great job, everyone. I learned so much, I can’t thank you guys enough.

Bry

Just had one of those carbs off an engine last week...And yes there is supposed to be a gasket between the intake manifold and engine block. Also there is three gaskets between the carb and the intake manifold as per the parts diagram.


They all should be in place if you want to get it to idle right. If you got an air leak at either of those joints you will be chasing your tail around trying to get the carb set up.

The one I had of had the same problem..rough or no idle. Works good now.

[panasonic]

Disregard my last post as I though it was an F15 as well....need new glasses I guess.

Never the less there still should be a gasket there between the carb and block. But for the life of me I cannot find it in the parts diagram for that engine.

I suspect it is a Oring type that sits in a groove on the carb.

So can the OP tell us if the flange on the intake side of the carb is smooth or has an Oring groove in it?

thanks

[pstephens46]

Maybe it's Rodbolt's favorite. Loctite 518

[boscoe99]

3M 5200 works well.

Use it in copious amounts. Also, use lots of it.

[pstephens46]

3M 5200 works well.

Use it in copious amounts. Also, use lots of it.

Wrong. Just found the SM online. Says to use a good bit of rootsauce.

[boscoe99]

I have not had much luck with rootsauce. It will work in one direction but not in the other direction.

Positive pressure it likes. It abhors a vacuum.

[pstephens46]

I have not had much luck with rootsauce. It will work in one direction but not in the other direction.

Positive pressure it likes. It abhors a vacuum.

You forgot to clarify abhor....

[rodbolt17]

yall be getting to obtuse.

that white stuff on the rubber plug is corrosion/fuel deposits.
remove it clean/replace it and clean the plug bore and pilot fuel jet and passages again.
on small chunk of that stuff in that tiny jet and she wont idle.

I see it all the time.
I stock plugs for them.

look at the carb diagram boscoe posted.
that is how your carb works.

I gotta run to the seafood house shortly and look at 6 of them on an old 225 3.1L.

lucky me.

[yellowtail]

Here's my engine:
Yamaha 15MSH Manufactured in 2007
Serial Number 684KS1057789

A 2-stroke to be sure... and I couldn't find a gasket listed on the parts diagram neither.

Bry