Your pump impellar might be stuck to the housing. The breaker might be tripping to prevent the motor from burning up. Have you tried toggling between forward and reverse? OR popping off the impellar housing and pulling that then switching it on? I just burned up a fuse in my johnson this weekend. I flipped it on like always on the way to the riding spot Water never came out the vent Checked and the bag wasn't full. I flipped the fill switch after my boat sat without running the pump for about a week in 90 degree heat. My rubber got stuck and burned up the fuse when i turned it on. Threw a new fuse in and toggled back and forth between fill and drain viola.
CURRENT: 2008 SANTE 210
2000 Mastercraft Xstar
2004,2005 Ski Centurion Avalanche C4
2003, Ski Centurion Cyclone
99,2000,2001, 2002 Ski Centurion Elite V/Hurricane/lightning
88 2001 Nautique