View Full Version : 87 115 yamaha oil tank draining of oil

mike richards
04-02-2006, 09:26 AM
"i have a 87" 115 yamaha 2stroke 4 cyclinder outboard. i am having a problem with my oil tank that is mounted on the upper head is draining while the boat is in storage. there is oil in the air cowling that is attached to the front of the carbs. i can't see any holes in oil lines. not sure why oil tank is not being refilled by main oil tank,could this be a oil pump malfunction. or a electrical problem. how do i determine which? and why is the tank draining when motor is not running?"

04-02-2006, 02:38 PM

You have to check if the pump motor is getting 12 volts when the ignition key is in the "on" position. If it is, then the pump motor is shot. If it is not getting voltage, you should check the float in the upper oil tank first; it might be stuck. If the upper tank is empty, you should get an alarm when you turn on the power. If no alarm, either the float is stuck, or there is a problem in the circuitry.

The oil tank might be draining through the vent hose, which feeds into the air cleaner/flame arrestor. I don't see how this could happen, but it is a possibility. Another possibility is that the oil pump is leaking into the crankcase, and from there out through the throttle bore on the lower carb into the air cleaner.


04-07-2006, 01:52 AM
is your battery dead or low from storage? this may sound strange but is very true. is all you need is a ground to turn pump on. when battery gets low enough it gets that ground and turns pump on oil is forced out of vent hose on top of oil tank and is plummed to air box then you get to clean up the mess .it like domminos