75 2 stroke mercury optimax motor problems

NEVER SAW ONE THAT DID

Is the kill switch ON?

This could be a lot of things. Have a computer scan done to see what the issue is. Could be a bad poppet or water pump. There is a sensor in the oil tank that can cause this too. Also the throttle sensor.

here you go

Mercury Optimax 115 Service Manual

50:1 But if your doing mostly low rpm cruising (trolling) then you could reduce that a bit to 75:1 to help reduce smoke. If you do mostly mid to higher rpm cruising, then 50:1 (1 pint to 6 gallons. )
Or 200mls in 20 liters if your Canadian.

It sounds like your high speed jet needs adjustment.

Once the fuel and oil are mixed, there is a problem with the seal of the generator set, which happens from time to time in use. It might indicates that the seal of the generator is out of order. Or it can be caused by excessive cleareance between piston and cylinder.
1. Pump membrane rot or degumming, so that diesel oil into the oil tank and oil mixing.
2. The injector has low opening pressure and poor atomization, which causes diesel oil to flow into the oil pan and oil along the cylinder wall.
3. The oil seal of the front end of the fuel injection pump is invalid, and the check hole cover of the gear chamber cover is removed.

buy a new one from Quicksilver dealer or a breaker !

You should drain your oil tank and check your sender to see if it is stuck or if the pick up is plugged.