Pool pump won't prime: what to check
Updated : · Piscines VP
A pump that won't prime is pulling air instead of water. Check the water level, fill the strainer with water, clean and lubricate the lid O-ring, open the suction valves and look for air leaks at the fittings. Never let the pump run dry for more than a few minutes.
Motor running but no water moving? The pump can’t prime: it’s pulling air.
Checks, in order
Turn the pump off before opening anything.
- Water level: halfway up the skimmer opening. Too low, and the pump sucks air.
- Strainer full of water: open the lid and fill the basket with a hose.
- Sealed lid: clean, uncracked O-ring, lightly lubricated (silicone pool lubricant). Hand-tighten.
- Valves open: skimmer and main drain on the suction side, return open too.
- Clean baskets: skimmer and pump strainer.
- Fittings: a cracked or loose fitting on the suction side lets air in. Look for bubbles in the strainer. See Air bubbles in the pump basket.
- Filter: bleed the air from the filter (air relief valve on top).
If nothing works
- The pump may sit too high above the water level or too far from the pool.
- The impeller may be clogged with debris.
- The shaft seal may be letting air in. See Pool pump leaking water.
Have the pump checked if it still won’t prime after these steps.
Don’t
Let the pump run dry “to see”. A few minutes is enough to damage the shaft seal.
Frequently asked questions
How long can a pump run without priming?
A few minutes at most. Without water, the shaft seal heats up and can be damaged, and plastic parts can warp. Stop the pump and find the cause.
Why is my pump hard to prime in spring?
After winter the plumbing is full of air or antifreeze, and seals are dry. Fill the strainer well, lubricate the lid O-ring and open all valves before starting.
Not sure of the cause? Take the 2-question diagnosis →
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