Why is the water pump for my irrigation system not turning on?

When you need to troubleshoot your irrigation pump, here are some options to consider in the process:


When you’re trying to keep your irrigation working well, there are few things as frustrating as water pump problems. What’s wrong with it? Why won’t it work? Here are some great ideas on troubleshooting your irrigation system’s water pump:

There’s no power getting to the pump.

If the pump is not turning on at all, you may want to start with the obvious and check to make sure the breaker is not turned off or tripped. If you reset a tripped breaker and it continues to trip, you may have an issue with the wire running to the pump or the pump motor itself. Other possibilities include the irrigation controller and/or pump start relay. Most irrigation controllers use an external pump start relay to send power to the pump. The irrigation controller sends a 24 VAC signal to the pump start relay. This 24 VAC signal energizes a coil that pulls in a set of contacts that completes the high voltage (usually 240 VAC) circuit and sends power to the pump motor. If the coil or contacts on the pump start relay are bad then the pump will not run. Likewise, if the irrigation controller is not sending that 24 VAC signal to the pump start relay, then the pump will not run. When dealing with electrical issues it is best to contact a qualified irrigation contractor or a licensed electrician.

The pump has lost prime.

All centrifugal pumps need to be primed. Yes, even “self-priming” pumps. “Priming” a pump simply means filling the pump casing and suction piping with water and ensuring that there is no air in the suction piping. Even “self-priming” pumps need at least their pump casings filled with water before they will pump. If a pump repeated loses prime between irrigation cycles, it probably means you have a leaking foot valve.

Suction lift is too high.

If your irrigation pump has been working fine and now seems to be struggling, you may need to check the suction lift. This can be a common problem during prolonged droughts when lake levels drop. The suction lift is the vertical distance between the water surface and the pump inlet. The friction losses through the suction piping and foot valve are also included in this calculation. Many times when the suction lift is getting too high the pump will sound like it has rocks in it. This noise is cavitation, which can literally destroy the internal components of the pump. If the pump’s suction lift is too high, you may be able to temporarily relocate your pump closer to the water source to remedy this problem.

There’s a blockage in the system.

Another reason your pump may be performing poorly is that the foot valve or the impeller may have blockages. Moss, leaves, and other debris can be drawn next to the intake screen on your foot valve restricting the amount of water that you pump can deliver. This also causes the suction lift to increase and may cause cavitation. The pump impeller can also become blocked with small particles such as pebbles and sand. Sometimes these small particles can pass through the intake screen and become lodged in the impeller vanes causing the pump performance to suffer.

Now that you know what to look for, it’s time to troubleshoot your system. For a more comprehensive pump troubleshooting guide visit our website. Contact us with any additional questions or to request help from our team of professionals.

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