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Pool Pump Humming But Not Working: What Should I Do?

Pool Pump Humming But Not Working

The pump is the heart of your pool. This important part creates the pressure that moves your pool water through the filters, chlorinators and all the other components of your pool’s circulation system. Recently you’ve started to worry because your previously crystal clear swimming pool is turning a muddy greenish color and you’re not sure why.

You know the pump is on because you can hear it. Did you make a mistake in your calculations for how long you need to run it? Is it the time of day? The wrong pump? What could be the reason for your pool pump humming but not working?

Unfortunately, several things could be the culprit. Some of the most common reasons are that:

  • You might have a bad capacitor.
  • Debris might be blocking the impeller and consequently disabling the pool pump.
  • There might be problems with the motor shaft.

What do all of these issues mean? Quite simply, your pool pump isn’t actually turning on. In this post, we will review why your pool pump might not be working and how you can fix it.

Pool pump not turning on

Pool Pump Not Turning On—What Does It Mean?

Before you attempt any of the following possible fixes to your pool pump, you should know that you need to possess basic electrical knowledge to get the job done safely and correctly. If you don’t, please do yourself a favor and bring in a professional to troubleshoot the problem and make needed repairs. Dealing with a broken pump is more dangerous and takes more pool expertise than knowing how to clean pool cartridge filters.

Even if you aren’t going to attempt the repair yourself, you may still want to know why you flipped on the power to your pump and hear humming but no actual signs your pump is working.

Bad Pump Capacitors

Capacitors are the small, black cylinders in your pump that look like batteries. Start capacitors are usually mounted at the back of the motor, while run capacitors are usually on the topside.

In a pool pump’s circuitry, the capacitor stores an electric charge that gets the pump motor running. Start and run capacitors store electric charges that start the motor and keep it running—no big surprise there.

As these parts age, capacitors tend to lose their charge-storing capabilities. Besides that, power surges and overheating can damage a capacitor. A bad start capacitor is incapable of kickstarting the motor, while a bad run capacitor can’t keep it running.

Signs Of A Bad Capacitor

How do you know if your capacitor is faulty? You might notice strange noises, overheating and performance issues.


One of the telltale signs of a bad capacitor is a motor that hums but doesn’t turn on—sound familiar?

A capacitor provides the torque that gets the pump motor up to speed. If you can get the motor to spin by manually pushing on its blades, then it’s very likely that a failed capacitor is the cause of your motor problems.


A bad capacitor may lead to the motor running at a higher amperage than it should. The higher the amps, the higher the wattage. Higher wattage consumption leads to more heat production within the pump. Because of this, pool motors with bad capacitors often overheat. However, most motors automatically shut down if they get too hot.

It is worth noting that overheating can be caused by several other issues as well, including a voltage upsurge, bad windings or an oversized impeller.

A Two-Speed Motor Only Working On A Single Speed

A bad capacitor is one of the reasons why a two-speed pump may only run on either low or high speed. Another cause is bad phase winding.

Testing A Pump Capacitor

It’s highly recommended that you hire a professional to test and/or replace your pump capacitor. If you accidentally mess something up during this process, you not only risk damaging the pump, but also hurting yourself.

No power to pool pump

Blocked Pump Impeller

A pool pump may also fail to start up if the impeller is clogged or blocked. This can happen if debris, such as leaves and swimming pool bugs, collect and build up within the pump.

To check the status of the impeller, you should:

  • Switch off power to the pool pump.
  • Unscrew the middle of the pump body and pull out the motor assembly.
  • Pull the gasket away for the disc-shaped impeller.
  • If any debris is found, remove it and clean the impeller until it can spin freely.

Problems With The Motor Shaft

Are you hearing humming briefly when you start your pump and then it shuts off?

If so, it is quite possible that the motor shaft is the issue. This is often an issue people experience when they attempt to open the pool for the first time that season because it’s fairly common for the motor shaft to seize up and suffer from corrosion during the off-season.

How can you tell if it’s the motor shaft that’s causing your problem? Disconnect the power to the pump, access the motor shaft and turn it by hand to loosen up anything that might be holding it in place.

If seizing was the issue, that should solve the problem.

What are some other pump issues you might find yourself having to navigate?

Pool pump motor not working

Pool Pump Motor Not Working

If your pool pump starts, but then shuts off on its own moments later, it’s often due to overheating.

One solution? Check to see if something is inhibiting the fan in the bottom vents, like leaves or mulch. You can also switch to running the pump at night when it’s cooler or, alternatively, providing more shade when you run the pump during the day. Finally, the pump might also turn itself off if it’s receiving inadequate power, or if some of its wires are loose or broken.

All in all, a pool pump that shuts itself off is never a good sign, and if you can’t solve the problem on your own, you need to reach out to a good pool pump professional as soon as possible.

No Power To Pool Pump: What To Do

If the pump doesn’t start at all, there’s a high chance it’s not receiving power. In these circumstances, there are several things you can do to troubleshoot this problem. Take the following steps to try to solve the problem on your own?

  • Make sure the pump switch is set to “ON.”
  • Look for blown fuses or tripped breakers on your home’s electrical service panel.
  • Check the electrical connections going into the motor for damage or insect infestations.
  • Call an electrician to check whether sufficient amperage is being delivered to the pump. The current being supplied to the pump may be insufficient.
  • Call your electrical provider to check to see if your home might be experiencing a power drop.
  • Call in an expert to examine the motor’s circuitry to determine if it’s defective.

What If My Pool Pump Doesn’t Pump Water?

If the pump is running but not pumping any water, it’s possible the pump might need to be primed. A pool pump can be primed by following these fairly simple steps:

  • Shut off all power to the pump.
  • Cut off the main drain by turning the diverter valve.
  • Turn the air relief valve on the pool filter clockwise to relieve any existing pressure (the pressure reading on the pool filter gauge should be zero).
  • Remove the pump lid.
  • Remove any debris you find in the pump basket.
  • Use a garden hose to fill the pump with water.
  • Replace the pump lid.
  • Turn the diverter valve to open the main drain.
  • Turn on the power to the pump.
  • Check whether water flow is restored to the strainer box at the top of the pump.
  • Wait until there’s water flowing out of the relief valve, then close it.

If the pump fails to catch on after several attempts to prime it, you might be dealing with an air leak in the suction, low levels of water in the pool or an obstruction in the water circulation line. These are things you really don’t want to deal with on your own, because they’re typically complex problems that should be addressed by a professional pool repair technician.

Generally, the technician will:

  • Check the suction and return valves.
  • Check the pump lid and the lid O-ring.
  • Check the drain plugs.
  • Check the pump basket, impeller, shaft seal, diffuser and diffuser gaskets.

What Causes A Slow Pump Flow Rate

Sometimes, the pump might be running, but the resultant flow rates are lower than normal. Some of the things that might lead to such a scenario include:

  • Dirty filters
  • A dirty pump basket
  • A clogged impeller
  • An air-leak

Some of these you may be able to deal with on your own. Others are better suited to a pool services company.

Pool pump squealing

Why Is My Pool Pump Squealing?

Ah, here’s one no one likes—especially your neighbors!

Under certain conditions, your pool pump can make loud screeching noises when it’s running. We’ve heard the sound described as “gargling stones” before. Not pleasant.

Pumps typically make such noises when they are starved for water. This may happen because:

  • Too many suction lines are closed. This makes it difficult for the pump to suck in enough water.
  • The skimmers are clogged. Debris may clog the skimmer so much that hardly any water gets through.
  • The pump may be inappropriate for your pool. For example, it might be too powerful, in which case you should downgrade to a pump that matches your pool size and requirements.
  • Worn bearings in the motor shaft can also cause screeching noises when the pump is running. It’s possible to change worn bearings, though it’s far better to simply switch out an old motor with a new one.

As you can see, pool pumps are serious business, and there are countless things that can go wrong—many of which may not be obvious just from you taking a quick look on your own. Moreover, if you make a mistake, it can end up being a costly one—both in time and money.

ABC Can Fix And Maintain Your Pool Components

The list of reasons why your pool might not be working properly is probably as long as the list of tasks you know you should be doing to keep your pool well-maintained—if only you had the time. If something strange seems to be going on with your pump, do yourself a favor and get in touch with the pool pros at ABC Home & Commercial Services. Our experienced pool specialists can help you with any problems you come across. Not only can we help with any repairs that need to be done, but we can also perform regular pool cleanings and give your pool a refreshed look by replastering or renovating it. No matter what your pool needs are, you can rely on ABC to get the job done right.

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