9.9 oil drip from air intake

[Sam]

I have had continued problems with this engine (new) almost from day one. It is a 2006 9.9hp 4 cycle with the 15 hp displacement. I had Yamaha headquarters confirm that the F9.9/T9.9 is not the correct manual - They sent me the 15 hp manual which has the right carburetor diagrams.

The problem has been stalling after running at speed and then throttling back to idle. General it would start right back up, but do the same. Now that I test it before going out I find that after a few minutes of open throttle it starts to stall.

I have taken apart the carburetor, installed an inline gas filter, cleaned the gas tank with acetone and added stabilizer to the gas.

I have noticed a few drops of oils coming from the air intake. It has a hose the feeds into it from the oil separator. I have changed the oil and filled it to 3/4 up the drip stick, just today so I do not know if that will fix anything. Disconnecting the hose seems to have fixed the problem, at least at the dock - I have lost confidence to go out until the problem is solved. Running this hose back into motor in only on US and Swiss models, all other vent to outside.

What is the function of the oil separator? Any fix for this?

Sam

[boats.net]

It's a crankcase vent, high oil level will result in oil blowing out through vent or low compression which will cause blow by past piston rings cause too much pressure in crankcase.

[Sam]

Air intake oil drip and stalling 9.9hp

After a year I took the engine back to the dealer to see if they could solve the stalling problem. I took in my gas tank along with the motor so that everything would be the same. I was told that the amount of oil dripping from the air intake was not a problem. They found no problem with the engine, but in passing said it ran better on their tank.

Turns out the brass male tank connector was cross threaded in the plastic fitting to the tank allowing air into the system, reducing the vacuum. Reinserting it correctly did not seal the leak. I used some Teflon tape to seal the air leak temporarily and engine runs great.

Moeller - the tank manufacture sent me a new fuel pick-up fitting for free (even though it was my fault) - they will be selling parts in the near future.

Sam