I HAVE A 25 HP MERC ENGINE AND KNOW VERY LITTEL ABOUT IT.ITS ELECTRIC START AND TURNS OVER BUT I HAVE NO SPARK.THE SERIAL NO. IS OA946482 AND ANOTHER NO. FOUND IS P/N 3397452A7 . TO UNDERSTAND HOW TO TEST THIS I NEED TO KNOW WERE I SHOULD FIRST GET CURRENT FLOW TO START THE ELECTRAL PROCESS...