1988 /1989 25hp Merc Model 1-025211g<br /><br />Over the last 4-5 years I have had replaced about the same number of "spark boxes". I dont use the boat that much and it took a while to see what was actually taking place. Something is "frying" the spark box after about 15-20 hours of use. Then motor only runs on one cylinder. What could be the underlying problem that is ruining the spark box(s). The boat mechanic says he is using factory replacement parts. <br /><br />Thank you for your help,<br />Forrest