I have a 1990 70 hp Johnson. It now runs good slow. However when I ope... read more I have a 1990 70 hp Johnson. It now runs good slow. However when I open it up it will run about 100 yards and alarm goes off and I lose all power. The motor still runs, I drop anchor and wait 15 to 30 minutes or till I get no alarm, start it and runs good till I do it again. I usually don't open it up and I just putt around. What is the problem here?