A pump that won't prime is a frustrating but usually quick fix. Here are the six real causes in order of frequency — most are DIY-able, one or two mean it's time to call.
1. Low water level in the pool
If water is below the skimmer opening, air is getting sucked in instead of water. Add water until the level is mid-skimmer.
2. Air leak on the suction side
Most common real cause. Look for:
- Loose pump lid O-ring (replace every 1–2 years)
- Cracked pump strainer basket housing
- Loose or rotted suction plumbing fittings
- Missing or degraded thread sealant on threaded joints
Fix: Coat the pump lid O-ring with pool-lube, hand-tighten the lid firmly, re-prime. If it still doesn't prime, trace the suction plumbing for leaks.
3. Clogged skimmer or pump basket
Pull both baskets, clean thoroughly, reinstall. Water can't move through a jammed basket.
4. Closed or stuck valve
Walk the plumbing from skimmer to pump. Any closed or partially closed valve blocks prime.
5. Failing impeller
If the pump runs but doesn't move water, the impeller inside the pump may be cracked or clogged with debris. Shut off power, remove the pump strainer, and inspect the impeller for damage or blockage. Replacement impellers run $60–$120; install takes an hour.
6. Dead motor capacitor
Pump hums but doesn't start = failed capacitor. $30–$80 part, 20-minute fix for a pro. Don't DIY unless comfortable with line-voltage electrical work.
When to call
If you've worked through 1–4 and the pump still won't prime, or it's humming without starting, call us. Pool equipment repair in South Florida — we diagnose and fix pump issues same-day in most cases.
Frequently Asked Questions
Air bubbles in the pump strainer basket while running, or a hissing sound near plumbing joints. Check O-ring seal first — it's the most common cause.
Need a pro to handle this?
Florida's Best Pools has serviced South Florida homes for 40+ years. CPO-licensed. Fully insured. 155+ five-star reviews.
