Troubleshooting Centrifugal Irrigation Pump Issues

It’s summer, which means irrigation systems are being put to work. But what if your client calls with a problem? Here’s a few troubleshooting tips from Munro Companies, Inc., manufacturers of water delivery products.

Evaluate The System

First, look to see if there have there been any changes to the system environment. New fencing could mean possible damage to pipework. Aeration or animals could also mean possible damage to pipework or sprinkler heads. If zones were added, the pump may now be undersized. Finally, consider the water source—are the levels lower than usual for some reason?

After you’ve considered changes on the property, look at the system for obvious problem areas. These include: leaking from the case or seal area; cracked or worn components; clogged filters or screens; and/or damaged gaskets in camlocks and o-rings.

Determine The Primary Issue

Here are some typical issues and their solutions:

• “My pump is running, but the sprinklers are not acting normal.”
  This is a reduced performance issue and is often the result of a change to the system environment. If nothing in the environment has changed, it’s time to check valves for proper positioning, check strainers for clogs, and check for suction leaks (TIP: wrapping plastic wrap around piping, fittings, or valves is a great way to check for air leaks – if there’s a leak, the plastic will tighten)
• “The pump is running, but there is no water coming out.”
  Once you’ve made sure that the pump is primed, this can be the result of a number of different issues, from a valve that’s not open, a clog in a strainer or a suction leak, to a damaged or worn seal or case. Start with a good inspection of the suction components. We estimate that over 80% of all pump issues are on the suction side.
• “The water comes out, then goes away. Then it comes out…”
  If this is the issue, the client is experiencing surges or flow cycles. As with the previous issues, check the suction side of the pump first, starting at the water source. Sometimes we see surging when a foot valve is not fully submersed or is blocked by debris.
• “The motor just sits there and hums.”
  In this instance, the shaft and impeller may not be spinning freely. Check that first, by inserting a wrench in the wrench slot, and rotating the motor shaft. If you cannot break the shaft free, you may need to take the pump apart to clean it. However, this can also be a voltage issue, which can be tested with a voltmeter.
• “When I turn the pump on, nothing happens.”
  First make sure that the breaker is turned on and the pump is plugged in (it’s happened to the best of us!). This could also be a voltage issue, in which case it’s best to call an electrician to troubleshoot or take the pump to a repair shop.
• “The pump runs for a little while and then stops and then starts again.”
  When the motor is cycling, the issue can be electrical, the pump controller (pump start relay) or possibly a float or manual on/off switch. If you are cannot find the issue there, you will likely need assistance from an electrician or repair facility.

Safety Precautions
Of course, when repairing systems, remember safety. When using any tool, refer to the manufacturer’s guidelines for proper use. ALWAYS turn the breaker off to work on a pump. (Some troubleshooting checks require the pump to be energized, so be sure the area is secure prior to the task. Be sure to turn the breaker off again if problem persists.) NEVER examine, make wiring changes, or touch the motor before disconnecting the electrical supply. Thermal overload protectors automatically reset and can close the electrical circuit without warning.

Founded in 1965, Munro is a leading manufacturer of pump stations, centrifugal and submersible pumps, pump controls, valves, fittings and accessories. Download a full 11-page Troubleshooting guide with tool lists, pictures, charts, flowcharts, and more here.

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