15 hp 2 stroke stalls after start up

[xort]

I have a 15 hp 2 stroke yamaha, less than 1 year old. I have a racor in line fuel water separator with recently replaced filter.

Engine has been running fine until yesterday. It would stall right after starting but after 3 tries, it ran fine. Now today it will not keep running. It will start with the choke on and with the throttle up, it will run for about 5 seconds before stalling. If I push in the choke it will stall sooner. If I throttle down towards idle it will stall right away.

New racor fuel water separator.
Changed plugs, old ones were pretty fouled.
Sprayed carb cleaner into air intake.
Pulled needle valve and sprayed carb cleaner there.
Oil mix should be close to 100:1.

Seems a very specific problem so the issue should be pretty specific as well.
Hoping to not need a rebuild of the carb.

Thank you

 

[tommarvin]

A few thoughts, don't spray carb cleaner in a two stroke it needs two stroke oil to lubricate the rings,
I think you need 50-1 two stroke oil.
Replace all on engine and off engine fuel filters, I know you replaced the inline.
The carbs dirty, you can take a carb off in less than 5 min. Now your scared fear not or your lazy which I'm sure your not.
Don't get in a hurry, tear carb apart, clean all openings with carb cleaner and compressed air, get rebuild kit with all gaskets, don't forget the gasket between the carb and carb adaptor, adjust the float etc, you got this, tear carb apart and clean well while your waiting for the kit to arrive.

 

[fhhuber]

Careful with the compressed air that you don't blow little parts away.

100:1 mix = short engine life.

A picture of the old plug helps with diagnosis, but it does sound like a plugged up carb, stuck float or other fuel starvation issue.

Inspect the fuel hoses, especially at connections.

Check the fuel tank vent (but usually they run longer than what you describe before starving if this is it.)

 

[xort]

100:1 is what the manual calls for. The old plug had black soot on it. All hoses are new. Checked the vent early on.

Suspect I need to rebuild the carb

 

[tommarvin]

I've never heard of 100-1 for a two stroke ever, it's always 50-1 after 25-1 break-in period.Are you sure your reading the factory service manual correctly.You could do a google search if that will make you feel better.
fhhuber says check for air leaks in the fuel hoses especially at fuel hose connections.

 

[flyingscott]

If you are going to run it 100-1 make sure you use Yamaha oil or something equivalent that is designed to run 100-1.

 

[GA_Boater]

Yes, xort read the manual properly.

This motor uses 25:1 for break-in, first 10 hours and 100:1 after breaking in. Yamalube, of course, is the recommended 2 stroke oil or any TC-W3 oil. It's all in the manual as xort said. http://www.yamaha-motor.com/assets/...8-34_9_9hp-15hp_684K-1038247-Current_1793.pdf

Did you use 25:1 during break-in? Are you getting any alarms? Have you checked or changed the fuel filter on the motor?.