Now and then with certain models of outboard motors, the oil injection system will appear to not work properly. However with most oil injection systems, this is a wrong diagnosis. It would seem that an outboard motor can damage itself by running lean, but in actuality, an engine wearing down due to running lean is not related to oil injection. Bearing failure and seizing in engines are oil related; running lean is a carburetion issue.
There are several ways to test the oil in the engine which can be done without a lot of technical knowhow. For example, if using a mercury outboard motor, mark the level of the oil in the tank with the engine perfectly vertical. Then add a known quantity of mercury oil, and mark the new level. If you have a separate tank, add an amount of fuel corresponding to the amount of oil you added in a 50:1 ratio. Run the measured amount of fuel through the engine. The oil level should go to the first mark, if it doesn’t, it’s not oiling at 50:1, and thus something is wrong.