2010 Yamaha MSH 15 hp 2 stroke Starting Trouble

Hello,

Having trouble starting a 2 stroke 15HP yamaha 2010- a friend brought it over to see if I could get it going but thus far I'm puzzled

Killswitch is in place, I cleaned the carburetor- idle jet was clogged-but other than that looked good-made sure gas was good- replaced spark plugs-

The engine will fire if i have left it alone say over night or for 48 hrs, usually only on the first pull-and only with the throttle wide open and choke open at same time- if it cuts off it then will not start again for the rest of the day (some kind of flooding issue?- float in the carb seemed to be working fine)

if it cranks I then have to quickly push the choke back in and back off the throttle- it then idles high (owner had messed with the air/fuel mixture screw on carb- i have it at 1 and a half turns as could not find the factory settings online?) one and half may still be too high but once it cranks and i have backed off the choke and throttle it usually cuts off before i have time to adjust fuel/air screw while its running

initially i wasn't convinced i was getting spark as i tried to hold plug(s) against the block and crank to see spark but had trouble seeing spark due to shaking of engine during crank (even at dark)....but the engine still fires sometimes (again always first crank of a new day after I've left it alone) so it must be getting some spark? thought maybe the coils were bad but again it still fires sometimes

Throttle linkage under tiller handle is loose/the ball at the end of cable slides out of the slot- i can manually put it back in but it slips out easily so that is just adding to the fun

And the tilt is so stiff its virtually impossible to raise/lower- there are 2 screws on the steering tube that i assume might make the tilt easier but have had no luck getting them to turn even with impact screwdriver

Any suggestions greatly appreciated-
jason

(tried to upload some pictures but having trouble)

Always include the model and serial # when asking for help.
They made a bunch of different models.

Try undoing the drain and squeeze the primer and see if fuel drips out of the carb?
You check the fuel pump diaphragm?

Do a compression and spark test, post results along with model#
Get an inline spark checker $6-7 way better than holding the plug.

Seems like it's either not producing a strong spark or it's running extremely rich.

Since you replaced the plugs and it still doesn't start consistently, you need to do a real spark test with a spark test adapter. They're cheap and easy to find at any auto parts store. That will tell you if it's actually producing a spark strong enough to jump the gap specified in the service manual (which is much larger than the gap at the spark plug tip). If you don't have the manual, I would guess 9mm is a good estimate. You have to rule out ignition first imo. If it turns out that the plug wires are showing strong spark, then I would focus on the carburetor again. That should be able to idle slowly regardless of whether the throttle cable is loose or not. Maybe the choke is choking when it shouldn't be. But generally, it sounds like your pilot screw might not in the right place.

Thanks for the replies!

Yamaha 15 HP 2 Stroke 15MSH 684K S 1072241

Date of purchase 11/08/2010

I have confirmed spark on both plugs- fuel does come out of drain on carb when screw removed and bulb primed

Had some luck starting the engine while manually adjusting the throttle lever on the carburetor as the linkage that attaches under the tiller handle is loose-

However while it was running i noticed gas slow dripping out of the carburetor- looks like it was coming from above the drain screw maybe the bowl gasket

so despite the gaskets passing the eye test while cleaning the carb i have order a carb kit/fuel pump...ill post back after it arrives

thanks!!!