You have just rewired a motor on a centrifugal pump. If the pump is generating little pressure and flow, what is the most likely cause?

The most likely cause of the centrifugal pump generating little pressure and flow after rewiring the motor is due to the wrong direction of impeller rotation from improper rewiring.

When a centrifugal pump is designed, the impeller is engineered to rotate in a specific direction to create the necessary centrifugal force to move water or other fluids effectively. If the motor is rewired incorrectly, it can lead to the impeller rotating in the opposite direction. This reversal can severely compromise the pump's ability to generate pressure and flow, as the centrifugal action relies on the momentum generated by the impeller spinning in the correct direction. Even though the motor may be operational, the misdirection will result in inefficient or negligible fluid movement, leading to inadequate pressure and flow.

The other potential issues, while they could cause performance problems, are not as directly linked to the symptoms observed in this scenario. A clogged pump typically leads to reduced flow but is less likely to affect pressure as dramatically as incorrect rotation. An inadequate power supply could cause the motor to run poorly or not start at all, but the scenario implies that the pump is running. Lastly, faulty motor bearings may lead to noise or even motor failure but wouldn't typically cause the pump to operate in a reverse or inefficient manner.