Pool Not Running? Start Here

Pulling up to a service stop and seeing a stagnant, debris-covered pool is one of the most stressful moments in pool service. The water looks dull, the surface is still, and you immediately wonder whether you’re facing a quick fix or a major equipment repair. This guide follows a practical pool troubleshooting flow for when the pool pump is not running: start with what you can confirm in seconds, then move methodically through pump startup issues, electrical power checks, and the less obvious human factors that can shut a system down. For pool service pros, having a repeatable diagnostic checklist reduces wasted time, protects equipment from further damage, and helps you explain the problem clearly to the customer.  

The fastest win is often the most visible: water level. If the water drops below the skimmer, the system can suck air, lose prime, and in some cases overheat until the pump shuts itself down. Newer skimmers may have a float diverter valve that automatically shifts suction to the main drain when the level falls, so a dirty surface does not always prove the pump has been off. Older pools without that diverter are far less forgiving. Low water can also leave behind confusing clues if the homeowner refills before you arrive, so treat water level as both a current condition and a possible recent event that triggered the problem.  

Next, move to the equipment pad and listen. A common pool pump failure mode is a bad start capacitor or run capacitor. When you toggle the pump and hear a hum followed by a click, the motor often cannot start and the capacitor is a prime suspect. Keeping common capacitors on the truck for popular pumps can turn a route-wrecker into a quick repair. If you hear nothing at all, you may be dealing with a burned-out motor or a power supply issue. Either way, you need to confirm voltage before you assume the motor is dead, because replacing a motor won’t fix a tripped breaker, a bad timer feed, or an upstream electrical fault.  

Electrical troubleshooting should be systematic. Use a simple non-contact voltage tester to confirm power at the timer, motor, and nearby outlets. Check the subpanel at the equipment first and flip breakers fully off and back on, even if they appear “on,” because a partial trip can be deceptive. If there’s no power, the main panel breaker may be tripped, hard to locate, locked, or poorly labeled. Many pool equipment circuits are on a double-pole breaker for 220V. Breakers can trip from an overheating motor, failing bearings that get louder over time, or extreme heat on older equipment. If voltage is inconsistent or low, an electrician may be needed, and low voltage can shorten motor life dramatically.  

Don’t ignore the simple and the strange. Standalone variable speed pumps often have a dedicated start-stop button, and a customer can stop the pump after swimming and forget to restart it, leaving the pool off all week. Some homeowners routinely shut systems down to avoid noise or reduce electricity use, which creates the same “dead pool” appearance as an equipment failure. If the pump won’t prime, consider a suction leak caused by a worn pump lid o-ring or heat damage from running dry. Melted threaded fittings and unions can pull air, and upgrading to higher-temperature schedule 80 fittings can help prevent repeats. Older pools may also have a “kill switch” that overrides the timer, sometimes located by a light switch indoors, so a quick scan for a hidden switch can save a long chase.