If the pressure switch is going bad it will do this, but it will also sometimes do it if your battery voltage is on the low side. Pump barely acheives enough pressure to shut off switch, but has no "bump" as it gets there so something as simple as boat moving in a wake or wave will trip it back to the run side for a brief moment. When batteries are good and fresh it doesn't happen--kind of the difference between barely closing a door or slaming it--the switch works best when it gets some slam. If it sounds like the motor slows down appreciably a few moments before it cuts off, rather than running normal right up tiil the stoppage, this might be you problem. Of course, the others are right about ANY small leak ANYWHERE is more likely.
