In Part 1 of this story on common pump problems at pool openings (find Part 1 here), we discussed causes and remedies of priming problems and what to do when the pump will not turn on. In Part 2, we’ll finish with what to do when the pump starts but then unexpectedly turns off, and when the pump runs rough or just doesn’t sound right.

RELATED: Pump Troubleshooting for Pool Openings, Part 1

What To Do: Pool Pump Turns Off

If your pool pump turns off by itself, either right away or after running for a period of time, this is a specific symptom that only has a few possible causes. Much like a pump that simply will not turn on, most of the troubleshooting steps for this pump problem involve electricity and testing for values at the electrical supply and at the pump. Electricity and water are a very dangerous combination, so you should never attempt to do ANY kind of electrical work or testing without a full understanding of the safe methods for doing this.

It will not cost a lot to get a handyman or an electrician to do some simple tests, so it’s well worth a few dollars to keep yourself safe. It can be a pressure-filled situation when a pool is not working, especially if there is an expectation that people will be swimming soon or you want to prevent the water from turning green. But no pool problem is worth doing something even a little bit dangerous, so forget about electrical testing if you don’t know how to do it properly and safely.

Pump turns off right away

If you turn on a pool pump and within 10 seconds (or even instantly) it turns off or trips the electrical breaker, then this could be one of a few things. The first question is whether the pump makes any noise when you try to turn it on. If your pump makes a humming noise and then trips out the electrical breaker then this is a very common problem.

Older pumps with internal rust and older brushes can almost develop a short circuit when the brushes are seized in place or lack the strength to start the motor into movement from a dead stop. If the motor is humming and not able to start up normally, there is a huge current pull to the motor. This results in heat building until the breaker trips, preventing a fire. When the circuit is cold you usually have somewhere between 5 to 10 seconds of humming before the breaker will trip out. During those few seconds when the pump is trying to start you can try using a soft rubber mallet and hitting the sides (not the back) of the motor section of your pump. Oftentimes this is just enough force to jog the motor slightly, which can break free the rust that is preventing the motor from moving.

Note: There is a fine line between jogging your pump motor with a mallet and taking out your pool frustrations on your broken pump. Sometimes the first blow feels pretty good, but remember: You are not trying to break anything — just troubleshoot the problem.

Jogging the motor with a mallet is the fastest test for a stuck motor but probably not the best one. If you want to be thorough, or if hitting pool equipment with a mallet does not feel technical enough for you, then you can also spin the motor shaft or impeller to get similar results. The only difference is that when you spin the impeller either by hand or with a screwdriver from the back of the motor, you need to do this with the power off. Tapping with a mallet is a little more dynamic in that you are jogging the motor while power is being applied.

If you are one of the lucky people able to get their motor started this way — either by whacking the pump or by spinning the shaft — then you are on a ticking clock. You might get another season out of the pump if you don’t start and stop it often, but more likely it will be a problem every time you turn off the pump. At this point, you should consider suggesting repair or replacement to the homeowner.

In my opinion, if you’re dealing with an older, single-speed pump, you shouldn’t spend a single dollar repairing it. Instead, get the homeowner to switch to variable speed. Variable-speed pumps are such a good idea and energy efficiency improvement over single speed pumps that single speeds are actually being outlawed in some places.

If rust was the problem, you should  most likely be able to stop the pump and start it again now that you got it going once. If you try this and your pump will not start again despite running just moments ago, you most likely have a failed start capacitor.

The good news is that a start capacitor is fairly quick and easy to replace. It’s one of the few repairs that I feel are worth the time and effort to get some more life out of an old pump. Gone are the days of rewinding motors, but a start capacitor replacement is fast and straightforward. Be warned that a capacitor stores an electric charge and can cause serious shocks even after the power has been disconnected. Additionally, capacitors have a nasty habit of exploding if you hook up the polarity backwards, so careful work is warranted.

Pool pump turns off after a while

If you have started up a pool pump and thought that everything went well, only to later discover that the pump is off again, there are a few things that you should check specifically. First, touch the motor to see how hot it feels. If a pool pump gets too hot it will turn itself off (thermal overload protection) to prevent fire. At least it is supposed to do that. However, the electrical breaker only monitors for temperature from current draw and not temperature from friction in the motor. If you discover the pump is off, the first thing you should do is check the electrical breaker that supplies the pump to see if it has tripped out.

A tripped electrical breaker can be in the “off” position or it can also be stuck in a middle, half-way kind of position. If this is the case, turn the breaker all the way off before you try to reset it and turn it back on. While it is possible that some sort of freak electrical occurrence caused the breaker to trip out, more likely the pump was drawing too much power for some reason and this caused the breaker to heat up and trip out. If this is the case, the breaker will likely reset once cooled and then run again for a while before overheating once more and turning off.

If you want to learn more about how pool pumps overheat and what you can expect moving forward from a pump with these specific symptoms, then you should read “Why Pool Pumps Overheat — And What You Can Do to Stop It” on my website. It was also published by AQUA Magazine in April 2017. In a nutshell, if your pump runs for a period of time and then turns off, you have started down a path that will eventually result in a dead pump (if not a pump fire) and you will definitely need to replace the pump.

The only other noteworthy thing worth mentioning for a pump that is tripping the electrical breaker is that you should differentiate between a tripped electrical breaker and a tripped GFI. A GFI (GFCI) is a ground fault (circuit) interrupter designed to essentially act as a hair trigger for amperage spikes. Current and voltage are inversely proportional so when one goes up the other goes down. When there is a short circuit, or a “ground fault,” then the voltage becomes zero.

If voltage were truly zero, this would technically make the current equal to infinity. Obviously this is not possible, but this is the electrical process that happens when a short circuit happens. The voltage drops to zero and the current races upwards towards infinity all within milliseconds.

A GFI breaker is specifically calibrated to detect a spike and disconnect the circuit. Some pool pumps are installed on GFI protected circuits while some are not. Since a pool pump is located in a wet area, it should certainly be protected with a GFI; however, this is not always the case.

Since a GFI is very sensitive you can sometimes get a GFI that trips out from the slightest bit of dampness in and around the motor. GFI’s can also become faulty themselves, so it may turn out that the pump is not even the problem after all. Actually, the same goes for regular household electrical breakers — they can simply wear out over time, and replacing defective breakers would be considered everyday work to residential electricians for this reason. If the homeowner has been using an electrical breaker as a switch to turn a pump on and off, this most likely caused the problem that you have now. An electrical breaker is NOT a switch, and is not designed to be used as one, especially for controlling a large electric motor. This is what they make motor starting switches specifically for.

RELATED: Technically Speaking: Variable-Speed Motors

Pool Pump Doesn’t Sound Right

If you have just opened a pool for the year and found the pump began making a funny noise, there could be a few different issues. The first thing you want to do is to identify the different types of noises so you can research the potential solution for each of these.

Humming pool pump:

As discussed in the section above, a humming sound coming from a pool pump usually indicates that the pump is stuck and not turning over either due to being rusted in place or from having a failed start capacitor. Usually a humming pool pump will only run for a new seconds before overheating and tripping the electrical breaker.

Bearing squeal:

If you notice a pump is making a new and strange noise, then you may be hearing metal bearings inside the motor that are making noise due to friction. Metal bearings will tend to sing, or scream, depending on how far along they are in terms of failing. Given enough time, the bearings will continue to get louder and louder as the amount of friction, rust and heat all increases.
If left long enough, the neighbors will eventually make it known that the pump is too loud, or potentially that the pump in on fire — this can happen. If you notice the pump is making the distinctive bearing squeal noise, you can potentially have the pump serviced and the bearings and main seal replaced. For some people this will be the best option. However, the cost of a new pump is low and labor rates are high for pump service.

If the pump is still fairly new, let’s say under five years old, then servicing the bearings may be the best bet. If the pump is in the seven to 10 year range, talk to the homeowner about investing in a newer pump that will last longer. If you have just opened the pool for the year and discover this sound, it is very likely that you can operate the pump for days or even weeks before the pump will get worse.

Sluggish or struggling pump:

If you notice that a pump turns on, or at least tries to, but the motor does not sound right, you may have a problem preventing the motor from spooling up to speed. The most common problem would be that the pump is only getting half as much power as it should. This is a very common pool pump problem that pool owners encounter when installing a new pool pump that comes factory wired for 240 volts on a 120 volt power supply. The pump turns on but sounds slow and sluggish. If you have a problem that sounds like this but the pump is not newly installed, it is possible that the electrical circuit feeding the pump has tripped out only half way.

Since 240 volts in a residential system is made from two opposing phases of 120 volts, it is possible that only half of the breaker has tripped out for some reason. Double check that the electrical supply for the pump is providing the correct voltage. If the pump is only 120 volts then it is not possible to be halfway tripped as can happen with 240 volt pumps. If you have a 120-volt pump that sounds sluggish and slow, I would consider bringing in an electrician to verify that there is not a problem with the wires supplying the pump, the breaker the pump is connected to, or the electrical connections inside the pump itself.

Pump is shaking or making loud popping noises:

If you notice the pump seems to be shaking, making popping sounds, hissing or rattling rhythmically, you may be dealing with pump cavitation.

Cavitation happens when the pump is being starved for water. When starved for water, the impeller creates a low-pressure zone and cavities, or bubbles, develop. As the bubbles pass through the pump, they are forced to compress back into liquid, which results in a sudden implosion that is violent enough to physically shake the pump and cause damage. These shockwaves within the pump sound like popping from the outside, kind of similar to how it would sound if there were small rocks moving around inside of your pump.

If you have pump cavitation, the first thing you should do is look into whether it is possible that there is an obstruction in the suction lines. If you have not done so, be sure to double check that the skimmer does not have the gizzmo or winterizing plugs still in place, as this would certainly cause cavitation in the pump.

A very common problem worth noting is that in the spring, many pool owners will be doing heavy vacuuming with their systems. If you vacuumed a pool for the first time this year and see the pump will no longer run, or is cavitating, it is entirely possible you have gotten something plugged in the suction lines. The standard process for blowing out stuck suction lines is to blow backwards from the pump towards the pool — never try to blow the restriction from the pool all the way to the pump. If you are doing any kind of heavy debris vacuuming in your pool, you should always be sure to use a pre-filter of some kind to prevent blockages in your buried plumbing lines. 

RELATED: Repairing a Pool's Circulatory System

Comments or thoughts on this article? Please email editors@aquamagazine.com

Steve Goodale is a renowned writer, humorist and swimming pool expert who lives in Ontario, Canada. You can learn more about Steve, as well as swimming pool construction, maintenance and repair (and have a few laughs) at his website: SwimmingPoolSteve.com.

Steve Goodale is AQUA Contributor of AQUA Magazine.