i recently got a boat with a 50hp evinrude on it. when i got it, it would fire right up and die. i rebuilt the carbs and it fired right up. i let it run for about 25-30 minutes. it was running very good. i went inside to get a drink, when i came back out it was not running. now i cant get it started again. there is no spark. i put new plug wires on it but nothing. the boat hadnt run for about 7 years before i got it. do you think it could be the coil packs?