2004 Yamaha 175 blowing fuses

[sandpiper16]

I was running up the lake yesterday and the engine just shut down. I figured out that is was the 20 amp trim/motor fuse in the engine. I replaced the fuse and it worked fine until I throttled the boat up. I then replaced it again. As long as I kept the boat around half throttle it worked fine. Does anyone have
any ideas. Thanks, Matt
One thing to add. I had to change over batteries and could not get the cables as tight as I would have liked to. Could this cause the fuse to blow.