I have a 1997 75hp Mercury 2-stroke. This past weekend we went out about 8-10 miles. Bottom bumped all day started it up after about 4 hours of sitting and the alarm goes off. I checked the oil level in the oil tank andit was good, water pump was working great. it ran and sounded fine. The alarm will sound even if the key is turned to the'on' positionand the engine is not running. any ideas?