PUMP TROUBLESHOOTING

At some point in time, all irrigation contractors must perform pump troubleshooting at the job site.  Here are a few steps you can follow to make the task a little easier.

  1. First, establish what the voltage is at the pump; use a multimeter to read this.

  2. Based on the voltage reading, refer to the wiring diagram on the silver motor plate. Make sure the black tracer wire is on the correct terminal for the power that is being supplied.

  3. Establish where the pump start relay is located. It should be located in the general area of the controller. A common mistake is mounting the relay a long distance from the controller. A long distance between the controller and the relay causes voltage drop, creating improper operation of the pump start relay.

  4. For pumps 3 hp and above, check proper rotation of the impeller. On the volute assembly on the front of the pump there is an arrow that points in the direction of proper rotation. IMPORTANT: This must be viewed from the rear of the pump, behind the motor. Once you have established what the rotation should be, clockwise (cw), or counterclockwise (ccw), look at the shaft of the motor and briefly put power to the pump. As the motor slows, you should be able to watch the shaft to see if it is turning in the correct direction. If the motor is turning in the wrong direction, refer to the wiring diagram and wire correctly.

  5. Verify that the correct size power wire (12, 14 gauge, for example) is being used to supply power to the pump in relation to the horsepower of the pump. Also, verify that the proper size circuit breaker is installed in the circuit breaker panel. Each pump is rated to certain amperage draw (each pump on its motor plate has the amperage draw). One sign that the power wire is too small is a higher than normal amperage draw. NOTE: It is common for many motor and engine manufacturers to indicate rotational direction in the opposite manner as the pump standard. That is, they refer to the rotation as viewed form the front of motor or engine. Pump rotation is determined by viewing from the back.

    Pump running backward - A centrifugal pump will still pump liquids, however, GPM and head will be a fraction of the published performance.