Could be the breaker but if you trailer your boat and don't flush the pump when you flush your motor it salts up and when you turn it on weeks later it trips your breaker. Had a buddy have the same problem, also heard if stays in the water it doesn't hurt them as bad. Bill
Any kind of buildup in the pump could cause it to trip. Getting seaweed wrapper around the impeller is a prime example of what could go wrong. Try taking the pump housing apart and cleaning it. If you have screen filters in the lines, try cleaning them.
I HAVE THE SAME PROBLEM ON A BOAT I JUST BOUGHT IN APRIL. THE BOAT WAS ONLY USED ONE SEASON, BUT I USED THE WASH DOWN QUITE A BIT THIS YEAR. I LOVE THAT WASH DOWN. I HAVENT HAD TIME TO MESS WITH IT. WHEN I DO, I POST WHAT I COME UP WITH. I HOPE YOU CAN DO THE SAME. I ALWAYS FLUSH THE MOTOR, NEVER THOUGHT ABOUT THAT PUMP AND I DO TRAILER.
SITTING HERE WITH MY FLOJET PUMP ALL APART. LOOKING AT IT, THE MOTOR WILL TURN ON BUT THE SWITCH TO THE PUMP WONT. MINE HAS A PRESSURE SWITCH ON TOP OF THE HOUSING. WHEN I TURN THE SWITCH ON MY CONSOLE, IT TAKES ABOUT FIVE SECONDS BEFORE MY CIRCUIT BREAKER TRIPS. I ASSUME THE PUMP MOTOR IS FILLING THE PUMP, BUT THE PRESSURE SWITCH AT THE TOP IS NOT ACTIVATING, THUS CREATING HEAT IN THE WIRE AND TRIPPING THE BREAKER. WHEW!! IT SOUNDS LIKE THE PUMPS YOU ARE USING REQUIRE A HEAVIER GAUGE WIRE FROM YOUR BREAKER TO THE PUMP. I AM GOING TO BUY A NEW PRESSURE SWITCH AND SEE IF THAT SOLVES THE PROBLEM. SMALLER WIRE, LARGE DRAW, MORE HEAT AND TRIPPING OCCURS.
JUST TOOK MY PUMP IN TO BE CHECKED. TWO YEARS OLD, IT IS A FLOJET 4.5 GAL PER MIN, 40PSI. THE MECHANIC OPENED IT FROM THE BOTTOM AND IT WAS FULL OF RUST. THE BEARINGS WERE SEASED. HE SAID IT IS COMMON FOR THESE PUMPS TO FAIL AT THE SEALES CAUSING WATER TO ENTER THE MOTOR OR IF IT IS MOUNTED IN A LOCATION WHERE WATER CAN DRIP ON IT. WHO KNOWS. $225.00 FOR THIS THING AND ITS A COMMON PROBLEM. WHAT A RIP OFF. I WILL DO SOME RESEARCH AND TRY TO COME UP WITH SOMETHING MORE HEAVY DUTY I GUESS.
HOPE THIS HELPED REG. SOUNDS LIKE YOU MAY HAVE THE SAME PIECE OF S PUMP THAT I DO, OR THE DINGBATS THAT BUILT THESE BOATS DIDNT TAKE INTO CONSIDERATION OF WHERE TO MOUNT THE THING. MINE IS LOCATED JUST ABOVE MY BILGE PUMP AND JUST BELOW AN 8" ACCESS HATCH AT THE TRANSOM.