I agree with Renos. It sounds like the pump isn't running where the system was designed; probably from valves being open/closed in a way that wasn't intended when the system was installed. If you shut all the output valves the water would have no place to go and the motor would have serious overload issues...that would then obviously not be the motor's fault. The motor is only responding to what the pump wants in terms of torque and Horsepower.
