Optimax 125 blowing fuse

[gunnysack]

 I recently purchased a boat with a 2011 125 optimax on it. My problem is every couple of outings it likes to blow a 20amp fuse when I turn the key and then it wont fire. Any idea what this could be? Thanks, Gunnysack

[Lee Smith]

Very first thing, check all your grounds.  How many cranks between blows? 

[Mike Cork]

I'm with Lee, save some heart ache and check grounds first. On the Merc motors there is a grounding wire from the motor to the trim plate that can be broken easily with a motor toter.