A humming pump that won't start usually means a bad capacitor.

Yes. If your pool pump makes a humming noise but the impeller doesn’t spin, the capacitor is the most likely culprit. It’s a cheap and easy fix.

A capacitor stores electrical charge to give the motor a jolt when starting. When it fails, the motor gets power but can’t get moving — hence the hum. You might also see the pump try to start, spin a little, then stop. Or it might run but at slower speeds, struggling to keep prime.

Another sign: visual damage. If the capacitor looks swollen, cracked, or has goo leaking out, it’s toast. Also check for a burned smell. A multimeter can confirm the capacitance, but if you have the hum-without-spin symptom and the pump hasn’t been running, just swap it.

One thing to rule out first: a stuck impeller. If something is jamming the pump, it’ll also hum. Turn off power, remove the pump lid, and try spinning the impeller by hand. If it spins freely, it’s likely the capacitor.

A $15 capacitor is a lot cheaper than replacing a whole pump or calling a serviceman.