I was trolling with my 25 hp. merc for about an hour when I deceided to run it hard for a few min. I slowed down to trolling speed and it sputtered and shut of. I could not restart it. I changed spark plugs which were wet and still could not restart it. After about ten min. I tried starting it and it still wouldn't start. For some reason I tried starting it by pulling on the starter rope . It sputtered and than ran ok for the rest of the day. What happened and why would it start by hand but not by using the battery and starter????? I would like to know in case it happens again 