If you have an oil injected motor and you disconect the fuel line to run out the gas in the carbs, you will fill them with straight oil, because the oiling system doesn't quit until the motor does. I see this many times each year mainly in 40-70 hp Johnson/Evinrude motors that siphion oil into the carbs as the gas evaporates making them impossible to start. Besides when running out the gas enough stays in the carbs even when ran out to keep the high speed jets in the gas, and all the gas at any rpm's goes through the jets. I would maybe change brands of gas, Marathon, Shell, not The corner cheapo and most of all not at the Marina. And the oil you use may be causing problems. I will always believe that oil fit's in the cheaper is not better catagory. Good Gas ,Good Oil, Good Treatment= No Problems. Good Luck

Hitman