My Yamaha 1986 115 hp 4 cyl 2 stoke leaks oil out of the reserve tank thru the oil pump and out the carb when the motor is raised all the way up. Others on the forum have posted similar issues. I believe the check valve inside the pump is stuck. The repair manual says to replace the oil pump. Someone has sugested that Yamaha as a check valve that can be installed in the oil line between the pump and carb. Is this check valve part Number 6R3-13183-00-00. Any other fixes would be helpful.