Pool Pump Not Working? Causes and Fixes by Symptom
The short answer
Pool pump will not start, hums, moves no water, or trips the breaker? Find the cause by symptom, decode VS pump errors, and compare repair costs.
In This Guide
A pool pump that is not working almost always shows one of seven symptoms: no power at all, a hum with no spin, a motor that runs but moves no water, a tripping breaker, screeching, shutting off by itself, or a leak under the motor. Each symptom points to a short list of causes, and most can be narrowed down with the breaker off and a few simple checks. Find your symptom in the table, then go to the section that covers it.
Which Pool Pump Problem Do You Have?
Match what you see and hear to the first column. The second column lists what usually causes it, and the third is the quickest check that separates those causes.
| What you notice | Most likely causes | First thing to check |
|---|---|---|
| Silent, no display, nothing happens | Tripped breaker or GFCI, timer or automation off, VS schedule, damaged wiring | Breaker panel and the GFCI test button |
| Motor hums but the pump does not spin | Failed start capacitor (single-speed), jammed impeller, seized bearings, low voltage | With power off, turn the motor shaft by hand |
| Motor runs, basket is empty or churning air | Lost prime, suction air leak, clogged basket or impeller, closed valve | Water level at the skimmer and the lid O-ring |
| Breaker or GFCI trips on startup | Water in the motor from a failed shaft seal, shorted winding, damaged wiring | Stop resetting it; look for water or rust at the motor |
| Screech, whine, or grinding | Worn bearings, cavitation, debris in the impeller | Whether the noise changes when you partly cover a return |
| Starts, then shuts off after a few minutes | Thermal overload from low voltage, blocked airflow, or bearing drag | Vents, clearance, and voltage at the motor |
| Water dripping between pump and motor | Failed shaft seal | Rust stains where the motor bolts to the pump |
| Variable-speed display shows an alarm | Drive detected a voltage, heat, prime, or stall fault | Write down the exact message before resetting |
How Do You Work on a Pool Pump Safely?
Turn the pump off at its breaker, not just at the timer or keypad, before you reach past the strainer lid, because a timer, automation, or freeze protection can start it without warning. Then let it cool: Hayward’s TriStar VS owner’s manual says to allow the motor at least 20 minutes before maintenance to avoid burns.
Capacitors can hold a charge after the power is off. Single-speed motors have small start and run capacitors, and variable-speed drives hold far more: Pentair’s IntelliFlo VS+SVRS installation guide warns that the drive’s capacitor bank holds a 230 VAC charge with no power to the unit, and says never to open the drive enclosure.
Call a licensed electrician for any voltage measurement inside the wiring compartment, a breaker or GFCI that trips again after one reset, a burnt smell, or a loose bonding wire. Hayward’s TriStar manual adds one rule worth remembering: if a GFCI cuts power to the pump without anyone pressing its test button, ground current is flowing, and the pump should not be used until a qualified person finds the fault.
Why Is Your Pool Pump Not Turning On?
A pool pump that makes no sound at all is either not getting power or being told to stay off. Check the power path in order: breaker, GFCI, timer or automation, and on a variable-speed pump, the display and schedule. None of these checks needs tools.
- Breaker. A tripped breaker usually rests in the middle position. Push it fully off, then on. If it trips again right away, go to the breaker section below.
- GFCI. Press test, then reset. Hayward’s TriStar manual says the test button should cut power and reset should restore it; a GFCI that does not do both is defective.
- Timer or automation. A mechanical timer’s clock stops during a power outage, so check the time and the on and off trippers. If a Hayward, Pentair, or Jandy controller runs the pump, try starting it from the controller’s manual mode before suspecting the pump.
- Wiring. With the breaker off, look along the conduit or cord for chewed or cracked insulation.
On a variable-speed pump, Hayward’s EcoStar troubleshooting guide says a completely blank display usually means the pump is not powered, from a tripped breaker or external automation, and that the supply should read 200 to 250 VAC. A lit display with a stopped motor usually means a schedule, a timeout, or an alarm. Short power blips stop these pumps too: the EcoStar shows “Power Interrupt” after an outage of less than 45 seconds and clears it on its own within 20 seconds.
Why Is Your Pool Pump Humming but Not Running?
A hum means power is reaching the motor but the shaft cannot turn. On a single-speed or two-speed motor, the usual causes are a failed start capacitor, an impeller jammed with debris, seized bearings, or low voltage. One test separates them: switch off the breaker and turn the motor shaft by hand, using the slot or flats under the cap at the back of the motor.
- Shaft spins freely: suspect the starting circuit. Inyo Pools’ motor troubleshooting guide lists the start and run capacitors and a stuck centrifugal switch (the governor) as the next checks, then a burned-out winding if those test good.
- Shaft is stiff or locked: something is binding. Hayward’s TriStar manual names an impeller jammed with debris as the cause of a motor that hums but does not start. If the impeller is clear, the bearings may be seized.
Shut the pump off as soon as you hear the hum, because a stalled motor heats up fast. Low voltage causes the same hum; Hayward’s TriStar manual says voltage at the pump must stay within 10 percent of the nameplate, which is 207 to 253 VAC on a 230 V pump.
The start capacitor
A failed capacitor often shows it: a bulged top, a split case, or oily residue. The replacement must match the microfarad (MFD) range and the voltage printed on the old one; 161 to 193 MFD, 250 V start capacitors were listed at SupplyHouse, Walmart, and Vetco for about $8 to $22. The same MFD range is also sold rated for only 110 to 125 V, which is the wrong part for a 230 V motor. If you know how to discharge one safely, a pool pump motor start capacitor on Amazon is a cheap first fix; if not, it is a short service call.
Variable-speed pumps have no start capacitor to swap. Hayward’s TriStar VS and Pentair’s IntelliFlo VS+SVRS use permanent magnet motors run by an electronic drive, and a stall shows up as a display error instead.
A jammed impeller
Pebbles, seed pods, or pieces of a broken basket can slip past the baskets and wedge in the impeller vanes. Reaching them means separating the motor from the pump housing: Pentair’s IntelliFlo guide has you remove the six bolts holding the volute to the seal plate, while Hayward’s TriStar manual recommends a qualified repair professional.
Why Is Your Pool Pump Running but Not Pumping Water?
If the motor runs normally but the strainer basket is empty, half full, or churning with air, the problem is hydraulic, not electrical. The pump has lost prime, is pulling air through a suction leak, is starved by a clogged basket or impeller, or has a closed valve upstream. The motor itself is usually fine.
Work from the pool toward the pump:
- Water level at least halfway up the skimmer opening, so the skimmer cannot gulp air.
- Valves fully open on the suction side, with the multiport handle seated on Filter.
- Baskets emptied, using the routine in our guide on how to clean a pool pump filter.
- Prime restored by refilling the housing and restarting, as in our steps to prime a pool pump.
- Air leaks traced if bubbles keep showing in the basket or at the returns; our guide to air in a pool filter shows how to find them.
- Impeller checked if the basket is full of water and the motor sounds normal but flow is still weak.
Hayward’s TriStar manual says priming can take up to 10 minutes, and to stop and find the cause if it takes longer. Variable-speed pumps enforce their own limits: the EcoStar posts “Prime Failed” after 15 minutes, and the IntelliFlo VS+SVRS raises a priming alarm after a default 11 minutes.
Do not let a single-speed pump churn air for long, because water is what cools and lubricates the shaft seal. A starved pump also shows up downstream as pool filter pressure that is too low. If the pump moves plenty of water but the pool stays cloudy or the gauge reads high, the fault is on the filter side, which our guide on why a pool filter is not working covers.
Why Does Your Pool Pump Keep Tripping the Breaker?
A breaker or GFCI that trips the moment the pump starts usually means current is leaking to ground: water inside the motor from a failed shaft seal, a shorted winding, or damaged wiring. Do not keep resetting it, because each reset sends current through a fault that sits next to water.
Hayward’s EcoStar troubleshooting guide narrows a tripping breaker to three suspects: a short to ground, the drive, or the breaker itself. Its checks start with wires shorting against the cover plate, then disconnecting the pump’s power wires and resetting the breaker; if it still trips with the pump disconnected, the fault is in the wiring or the breaker. Hayward also notes that GFCI breakers are more prone to nuisance tripping, so an electrician should confirm the trip is real before the pump gets the blame.
Rust streaks under the motor, water at the motor vents, or corrosion where the motor bolts to the pump point to a seal that has leaked for a while. The same Hayward guide says repairs after water floods the drive or motor may not be covered by warranty.
The GFCI itself is required. The 2020 National Electrical Code, in NEC 680.21(C), calls for Class A GFCI protection on outlets supplying pool motors on branch circuits rated 150 volts or less to ground and 60 amps or less, and 680.21(D) extends that to any replacement pump motor installed for maintenance or repair. If an older pump never had GFCI protection, its replacement needs it.
What Does a Loud, Screeching, or Grinding Pool Pump Mean?
A steady screech or high whine that is there whenever the motor runs, even with water flowing freely, usually means worn motor bearings. A rattling, gravelly roar that changes with flow is cavitation or debris in the pump. Hayward’s TriStar manual lists four sources of pump noise: suction air leaks or cavitation, vibration from poor mounting, debris in the housing, and noisy bearings.
Hayward ties bearing noise to wear, rust, overheating, or a leaking seal that lets chlorinated water into the bearings and washes out the grease, which is why the manual says seal leaks should be fixed at once. The bearings sit inside the motor, so replacing them means removing and taking apart the motor; weigh that labor against a replacement motor in the cost table below.
Cavitation is the pump trying to pull more water than the suction side can supply. Hayward lists restricted or undersized suction lines, a low water level, and wide-open returns as causes, and suggests a test: hold a hand over a return fitting or fit a smaller eyeball, and if the noise drops, throttle the returns or fix the suction restriction. For buzzing and vibration, Pentair’s IntelliFlo guide says to mount the pump securely on concrete rather than a wooden platform for the quietest running.
Why Does Your Pool Pump Shut Off by Itself?
A pump that starts normally, stops after a few minutes, and later restarts on its own is usually tripping its thermal overload. The motor got too hot, the overload cut power, and it reset once the motor cooled. The heat comes from low voltage, blocked ventilation, or a motor working against dragging bearings or a partly jammed impeller.
Inyo Pools’ motor guide says most pump motors carry this automatic thermal protection and warns that running in an on-off cycle for long periods burns the motor out. It also notes that a motor wired for 230 V but fed 115 V shuts down after about 3 to 5 minutes. Hayward’s TriStar manual traces a motor that shuts off to low voltage at the motor, frequently caused by undersized wiring.
Airflow matters as much as voltage. Hayward calls for free circulation of air for cooling, and Pentair’s IntelliFlo guide asks owners to shade the motor, ventilate any enclosure, and keep the fan cover and cooling fins clear. Variable-speed pumps react more gradually: the IntelliFlo VS+SVRS slows down when its drive passes 130 degrees, while Hayward’s TriStar VS and EcoStar display a drive overheated message and stop. Before blaming heat, confirm that a schedule or freeze protection program is not simply starting and stopping the pump.
Why Is Water Leaking Under Your Pool Pump Motor?
Water dripping from the gap between the pump housing and the motor is almost always a failed shaft seal. The seal has a stationary half pressed into the seal plate and a rotating half that rides on the impeller, and it keeps water from following the shaft into the motor. Once it fails, water reaches the bearings and windings, so fix it as soon as you see it.
Running dry is the usual killer: Hayward’s manual says water cools and lubricates the seal, and Pentair’s guide warns that a dry run damages it and starts a leak. The part is cheap. Generic PS-201 seals were listed at about $8 to $11 on eBay and at Inyo Pools, and Hayward’s SPX1600Z2 at about $19 to $38 at epoolsupply, Bath and Spa Parts, and Inyo Pools; order by your pump’s model, since seals differ.
The labor is the real job, since the motor comes off the pump and the impeller comes off the shaft. Pentair’s guide calls for silicone on the new seat’s metal portion and an overnight cure, and Hayward says only qualified personnel should attempt it. Angi’s pool pump repair cost guide puts professional seal replacement at $100 to $250.
Shop pool pump shaft seal kits on Amazon
Leaks elsewhere are different problems. Drips at the lid usually trace to the lid O-ring, drips at the pipe connections to the union O-rings, and a cracked strainer housing is often freeze damage from a pump left full of water. Draining the equipment at closing is part of winterizing a pool filter.
What Do Variable-Speed Pump Error Codes Mean?
Variable-speed pumps report faults on the display, so write the exact message down before you clear it. Most messages fall into four groups: supply voltage, overheating, priming, and stall or overload. The table lists messages from Hayward’s TriStar VS owner’s manual, Hayward’s EcoStar troubleshooting guide, and Pentair’s IntelliFlo VS+SVRS installation guide.
| Pump | Message | What the manufacturer says it means | First step |
|---|---|---|---|
| Hayward TriStar VS | DC voltage high / DC voltage low | Drive’s internal DC voltage rose above 400 VDC or fell below 230 VDC | Have line voltage checked; it should be within 10 percent of rated |
| Hayward TriStar VS | Drive overload | Motor current is too high | Check impeller, diffuser, shaft seal, and motor |
| Hayward TriStar VS | Startup failed | The drive could not start the motor | Check impeller, diffuser, shaft seal, and motor |
| Hayward TriStar VS | Drive overheated | Drive components overheated | Clear the motor’s airflow path |
| Hayward EcoStar | PFC-Hi | Mains supply above 280 V; not a pump fault | Breaker off for 2 minutes, then back on |
| Hayward EcoStar | AC Mains Low | Mains supply below 185 VAC | Electrician to correct the supply |
| Hayward EcoStar | Prime Failed | No prime within 15 minutes | Suction leaks, lid O-ring, baskets, filter |
| Hayward EcoStar | Stall error / Drive Failed to Start | Three failed start attempts; most often water getting in | Check for water damage and a shaft that turns freely |
| Pentair IntelliFlo VS+SVRS | Power out failure | Supply below 170 VAC | Have the supply voltage checked |
| Pentair IntelliFlo VS+SVRS | Priming error | Not primed within Max Priming Time; permanent alarm after five attempts | Fix the suction side, then reset |
| Pentair IntelliFlo VS+SVRS | Over current | Drive overloaded or a motor electrical problem | Power off and check that the impeller turns freely |
Hayward’s TriStar manual says its errors reset with Stop/Resume or a power cycle, although “Drive overload” sometimes clears only with a power cycle. Pentair’s guide keeps the buttons locked until the alarm is acknowledged with Enter and cleared with Reset after the fault is fixed. An error that comes straight back after a reset is not a glitch. Newer models such as the IntelliFlo3 VSF and Hayward’s MaxFlo VS use their own message lists, so match the message to your pump’s manual; Hayward publishes the full EcoStar troubleshooting guide with step-by-step checks for each message.
Should You Repair or Replace a Pool Pump?
Repair when the fault is an inexpensive part on a healthy motor: a capacitor, a shaft seal, or a cleared impeller. Replace when the windings or bearings have failed on an older pump, when water has damaged a variable-speed drive, or when the repair approaches half the price of a new pump, the cutoff HomeAdvisor’s pool pump cost guide suggests.
| Repair | Typical part price | Typical professional cost |
|---|---|---|
| Start capacitor (161 to 193 MFD, 250 V) | $8 to $22 | $100 to $250 (Angi, electrical repairs including capacitors) |
| Shaft seal | $8 to $11 generic PS-201; $19 to $38 Hayward SPX1600Z2 | $100 to $250 (Angi) |
| Single-speed motor, 1 to 1.5 HP | $185 to $365 (stock built before the 2025 rule) | $200 to $800 for most motor replacements (HomeAdvisor) |
| Variable-speed replacement motor (Century VGreen 165) | $550 to $615 | Same HomeAdvisor range; some jobs reach $2,000 |
| Variable-speed motor and drive (Hayward TriStar VS power end) | $1,130 to $1,230 | Not separately quoted |
| Complete variable-speed pump (MaxFlo VS 500, TriStar VS 900, IntelliFlo3 VSF) | $1,380 to $2,200 | $800 to $2,500 installed (HomeAdvisor) |
Part prices are typical ranges from retailer listings at SupplyHouse, Walmart, Vetco, eBay, Inyo Pools, epoolsupply, Bath and Spa Parts, Electric Motor Warehouse, Poolweb, Bestpoolshop, and Leslie’s, not current quotes. Budget a shaft seal into any motor swap, since motor sellers such as HD Supply say to replace the pump seal whenever a new motor goes in.
Can You Still Replace a Pool Pump With a Single-Speed Model?
For most in-ground pools, no. Two U.S. Department of Energy (DOE) rules push both complete pumps and replacement motors toward variable speed, so the practical replacement for a failed 1.5 HP single-speed pump or motor is a variable-speed one.
Complete pumps, since July 19, 2021. DOE’s dedicated-purpose pool pump standard (10 CFR 431.465) sets a minimum weighted energy factor for pumps manufactured on or after July 19, 2021. Pentair’s white paper on the rule explains that self-priming pumps between 0.711 and 2.5 hydraulic horsepower, typically about 1.2 to 5.0 total horsepower, face the high bar: variable-speed pumps meet it easily, while single-speed and two-speed pumps are unlikely to. Smaller self-priming pumps under 0.711 hydraulic horsepower and some above-ground pumps can still qualify with an efficient single-speed motor, and three-phase pool filter pumps are exempt from the performance requirement.
Replacement motors, since September 29, 2025. The 2021 rule covered complete pumps, so a separate rule (88 FR 66966, published September 28, 2023) now covers the motor itself. Under 10 CFR 431.485, summarized on DOE’s dedicated-purpose pool pump motors page:
- 1.15 to 5 total horsepower: must be variable speed if manufactured on or after September 29, 2025.
- 0.5 to under 1.15 total horsepower: must be variable speed if manufactured on or after September 28, 2027. A DOE enforcement policy says DOE will not seek civil penalties for these small motors manufactured before March 26, 2029.
- Under 0.5 total horsepower: must reach at least 69 percent full-load efficiency from September 29, 2025.
Total horsepower (THP) is the nameplate horsepower multiplied by the service factor. Pentair’s example: a 1.0 HP full-rated motor with a 1.65 service factor and a 1.5 HP up-rated motor with a 1.10 service factor are both 1.65 THP, so read both numbers off your nameplate before shopping. A working pump never has to be replaced, and both rules apply by manufacture date, which is why single-speed motors built before the deadlines still appear in retailer listings.
Related Guides
- How to Prime a Pool Pump in 7 Easy Steps: the full priming routine for a pump that runs but moves no water
- Air in Pool Filter: Causes, Diagnosis, and Fixes: find the suction leak behind bubbles in the basket and a lost prime
- How to Clean a Pool Pump Filter: Strainer Basket and Main Filter: clear the baskets that starve the pump of water
- Why Is My Pool Filter Not Working? 8 Causes and Fixes: filter-side problems when the pump itself is healthy
- Pool Filter Repair: DIY Fixes, Costs, and When to Call a Pro: leaks, valves, and repair costs on the filter side of the pad
- Best Above-Ground Pool Filter: sand and cartridge filters and pump combos for above-ground pools
Frequently Asked Questions
How do I know if my pool pump capacitor is bad?
How do I reset my pool pump?
Why does my pool pump turn on by itself at night?
How do I know if my pool pump is 115 or 230 volts?
Is it worth replacing just the pool pump motor?
Pool Filter Guide is an independent research site. Every guide is built from manufacturer owner's manuals, spec sheets, and published standards, and names its source in the text. We do not test products in-house, and no brand pays for placement or a better verdict.