Pool Pump Not Working: Priming, Seal and Capacitor Checks

What is your pool pump doing? Start with the symptom

Match what you see and hear to a row below. The owner checks are visual and done with power off. Everything in the last column belongs to a licensed tech.

Power comes first. Pentair's manual says to disconnect power at the circuit breaker before servicing,^[1] and Fluidra adds that you should not do maintenance with wet hands or on wet equipment.^[3] Pumps should also sit on a GFCI-protected circuit that you test routinely.^[2]

If the pump is fine and the water stays cold, see pool heater not heating.

A pool pump that hums but will not spin

A hum with no spin means the motor is getting power but the shaft is not turning. The usual suspects are a failed start capacitor, a jammed impeller or seized bearings.

How the parts connect

Where the hum-and-no-spin parts sit

1. 01

   Strainer basket

   Catches debris before the impeller

2. 02

   Impeller

   Can jam on debris

3. 03

   Shaft seal

   Between the wet end and the motor

4. 04

   Bearings

   Gritty or noisy when worn

5. 05

   Start capacitor

   Behind the motor cover

Switch it off right away. A motor left humming heats up fast and can turn a small repair into a dead motor.

Capacitor checks and replacement

A start capacitor gives the motor its kick. When it fails, the motor hums and may not move at all. The part is cheap, but it is also the hazard: Pentair warns that the capacitor bank can hold a 230-volt charge even with the power off.^[1]

It sits behind the motor cover, so capacitor replacement is tech work, not a weekend job. Fluidra likewise says to contact a qualified service engineer after a breakdown instead of attempting repairs.^[3]

Pro tip

Treat the capacitor cover as a no-go for owners: the part can hold a charge with the power off, so leave it to a licensed tech.

When the motor itself is the problem

With the breaker off, look for debris at the impeller through the open basket. A shaft that will not turn freely suggests a jammed impeller or bad bearings. A gritty or noisy turn points to bearings, which means the motor is near the end.

Electrical work has a licensing edge too. The Arizona Registrar of Contractors (ROC) R-6 scope excludes "electrical work beyond the first disconnect." Rewiring a motor feed or replacing a breaker is not the same as swapping a capacitor, so confirm the class covers the job.

Why a pool pump will not prime or move water

Most "won't prime" calls are air getting into the suction side, not a dead pump. Work through the causes in this order: low water level, a full strainer basket, a stuck skimmer weir, a dry or cracked lid O-ring, a closed valve, and a clogged line.

How it works

Priming checks in order

1. 1

   Step 1: Low water level

2. 2

   Step 2: Full strainer basket

3. 3

   Step 3: Stuck skimmer weir

4. 4

   Step 4: Dry or cracked lid O-ring

5. 5

   Step 5: Closed valve

6. 6

   Step 6: Clogged line

Fill the pump basket housing with water, seat the lid evenly, and restart. If it primes briefly and then loses it, an air leak is the likely reason. Check the lid O-ring, drain plugs and suction-side unions, and tighten plastic unions by hand, not with tools.

Never let the pump run dry while you troubleshoot. Pentair states that dry running can damage the mechanical seal and cause leaks.^[1]

A clean basket and a sealed lid with still-weak flow can mean a restricted filter, covered in pool filter repair and replacement. A cracked housing or damaged impeller is a wet-end repair for a tech.

Pump failures after rain or monsoon storms

Monsoon season (July to September) brings debris and power events. Check the basket for leaves and silt, look at the GFCI, and have a tech inspect the timer box if you suspect water inside.^[2]

Why is my pool pump leaking? Shaft seal and seal replacement

Find the source before you decide anything. Lid O-rings, unions and drain plugs are cheap and visible. A housing seam is more serious.

A drip near the motor shaft, where the wet end meets the motor, points to the shaft seal. That one needs quick action. A failed shaft seal lets water travel toward the motor bearings, and it can even show up later as breaker trips. Switch the pump off and arrange an inspection.

Shaft seal replacement is a sound repair when the motor is healthy. If the bearings are already rusty or noisy, replacing the motor or pump is usually the better route.^[1]

If the water level keeps dropping and you cannot find a pump leak, the loss is elsewhere. See pool leak detection and repair.

Resetting a pool pump that trips or will not start

Reset the breaker once, after checking for standing water or obvious moisture. Also check the timer, the GFCI, and any reset button on the motor (location varies, so use your manual).

Checklist

Before you reset the pump

0 of 5 ticked

• Check for standing water or moisture
• Check the timer setting
• Check the GFCI status
• Look for a reset button on the motor
• Reset the breaker once only

Tick them off as you go. Nothing is saved or sent.

If it trips again, stop. A second trip points to a wiring fault, water in the motor or failing windings. Resetting repeatedly will not fix any of those.

A motor that shuts itself off may be overheating, not electrically faulty. Phoenix summer highs reach about 106°F, and a motor in direct sun or a closed enclosure runs hotter. Check airflow, shade and a blocked strainer, let it cool, and restart once.

Cracked or brittle wire jackets or conduit near the pump are reasons to stop and call a licensed tech.

Repair or replacement, and Phoenix service providers

Cheap-part signs are a capacitor, a seal or an O-ring on an otherwise sound pump. Replacement signs are noisy or rusty bearings, burned windings, a cracked housing or repeated breaker trips.

Phoenix-area pool companies' own websites, checked October 2026, list diagnostic or service-call fees mostly from $85 to $95. They show minor pump repairs at $200-$400 and motor rebuilding or replacement at $350-$700. These are generic guides, not quotes, so get an itemized written estimate.

Key takeaways

1. 01Service-call fees mostly run $85 to $95
2. 02Minor pump repairs are shown at $200-$400
3. 03Motor rebuilding or replacement is shown at $350-$700
4. 04Capacitors, seals and O-rings are cheap-part repairs
5. 05Noisy bearings, burned windings or repeated trips point to replacement

Once repair stops making sense, see pool pump replacement cost. Replacements may also need to meet energy-efficiency rules, which the Pool & Hot Tub Alliance says apply to many pumps replaced after July 19, 2021.^[4]

Arizona requires an ROC license for pool repair. R-6 or CR-6 covers service and minor repair, and B-5, B-6, KA-5 or KA-6 cover broader work. Check the class, bond and Recovery Fund status on the ROC Contractor Search.

The ROC states that the Recovery Fund pays up to $30,000 per residential property owner. For the full class breakdown, see R-6, B-5 or KA-5 license classes.

Any contract over $1,000 must be in writing with the license number and the ROC complaint notice. For hands-on service, start with pool pump repair and replacement.

Pool pump not working FAQ