Yamaha oil injection

[markduffy]

I have a 1986 Yamaha 40 hp 2 stroke outboard motor.
After sitting a day or two the bottom cylinder fills with 2 cycle oil from the oil tank.
Any thoughts on how to correct this situation?

 

[99yam40]

oil pump check valves leaking

 

[markduffy]

Is that the plastic piece in the oil line between the oil pump and carburetor?

 

[99yam40]

1990 up had the inline check valves, I guess your motor has them in the oil pump
might buy the later ones and install in the lines

 

[markduffy]

i have plastic pieces in my oil lines between the oil pump and the carburetors.
Are those the check valves you are referring too?

 

[99yam40]

Have you looked at a parts breakdown for your motor and for 1990 and later model?
if not do so and see what it tells you.

but then someone may have upgraded the oil pump and lines in the past