A pool pump that won’t prime is one of the most frustrating issues for pool owners. Without a properly primed pump, water won’t circulate, your filter won’t work, and the pool can quickly turn cloudy or green. Whether your pump won’t catch prime or loses it after a few minutes, this guide will walk you through all the common causes and solutions to get things flowing again.
What Is Priming a Pool Pump?
Priming your pool pump means removing all air from the suction side of the system so water can flow freely through the pump and into the filter. Most pool pumps are not self-priming, so they rely on gravity and water pressure to establish this flow before the motor can do its job.
1. Pump Basket Not Filled with Water
Why it happens:
If the pump basket is dry or only partially filled, air is trapped in the system and the pump can’t build suction to prime.
Direct Answer: A pump won’t prime if the pump basket isn’t filled with water, preventing it from pushing water through the system.
How to fix it:
- Turn off the pump.
- Open the pump lid and fill the basket completely with water.
- Replace the lid tightly and turn the pump back on.
Recommended Product:
Hose-End Shut-Off Valve – Allows easy control of water when filling your pump basket during priming, especially in remote equipment pads.
2. Air Leak in the Suction Line
Why it’s a problem:
Even a tiny air leak on the suction side (between the skimmer and the pump) can prevent your pump from priming properly. You may see bubbles in the pump lid or return jets.
Direct Answer: Air leaks before the pump disrupt suction and make it impossible to build enough pressure to prime.
How to fix it:
- Inspect the pump lid o-ring for cracks and apply silicone lubricant.
- Check suction-side unions, valves, and pipe fittings for air gaps or loose connections.
- Use a leak detection dye or shaving cream to spot leaks while the pump is running.
Recommended Product:
Aladdin Magic Lube II – Non-toxic silicone lubricant that improves seals on pump lids, valves, and unions to eliminate air leaks.
3. Clogged Skimmer or Suction Line
Why it causes priming failure:
A blockage in the suction line, skimmer basket, or pump strainer will restrict water flow, keeping the pump from establishing prime.
Direct Answer: A clog in the suction line prevents water from reaching the pump, stalling the priming process.
How to clear it:
- Turn off the pump and remove any visible debris from skimmer and pump baskets.
- Use a drain bladder or reverse water pressure to push clogs out of the suction line.
- Check for tight turns or kinks in flexible plumbing lines that can trap debris.
Recommended Product:
Drain King Drain Bladder – Connects to a hose and uses high-pressure water to push clogs from suction lines without disassembling pipes.
4. Low Water Level in the Pool
Why it matters:
If the water level drops below the skimmer intake, the system will suck air instead of water, causing priming to fail repeatedly.
Direct Answer: A low pool water level introduces air into the suction line, preventing the pump from maintaining prime.
Fix it fast:
- Top off the pool so the water level is halfway up the skimmer opening.
- Make sure the weir flap (skimmer door) isn’t stuck closed.
- Inspect for leaks or excessive evaporation if the water level drops frequently.
Recommended Product:
Fill-O-Matic Automatic Pool Water Leveler – Automatically maintains your pool’s ideal water level to prevent suction airlock and priming issues.
5. Pump Lid Not Sealing Properly
What to look for:
The pump lid must form a perfect seal for priming to occur. Warped lids, cracked o-rings, or dirt under the seal can introduce air.
Direct Answer: A pump lid that doesn’t seal tightly lets air in, disrupting the vacuum needed to prime the system.
Steps to fix:
- Clean the lid and gasket with a damp cloth.
- Replace worn or stretched o-rings.
- Apply a thin layer of silicone lubricant for a better seal.
Recommended Product:
Hayward Pump Lid and Gasket Replacement Kit – Includes a clear lid and high-quality o-ring for reliable priming and leak prevention.
6. Incorrect Valve Positions
How valves affect priming:
Pool systems with multiple suction ports (skimmer, main drain, cleaner line) use diverter valves. If they’re not set correctly, water won’t flow properly for priming.
Direct Answer: Improper valve settings divert suction away from the pump, causing it to run dry and fail to prime.
What to do:
- Open the skimmer line fully and partially close the main drain line to assist with initial priming.
- After prime is established, adjust valves to your normal operating settings.
- Mark the “priming” positions for future reference.
Recommended Product:
Jandy NeverLube 3-Way Valve – Smooth-operating diverter valve that helps manage suction flow without leaks or corrosion.
7. Pump Motor Running but No Water Movement
What could be wrong?
If the motor is spinning but you’re not seeing water flow after a minute or two, it could be a clogged impeller, stuck check valve, or damaged diffuser.
Direct Answer: A spinning motor with no water movement likely means an internal blockage or component failure inside the pump.
Troubleshoot it:
- Turn off power and inspect the impeller for debris.
- Check the diffuser and shaft for cracks or damage.
- Replace worn-out parts with compatible components.
Recommended Product:
Pentair Impeller and Diffuser Kit – OEM parts for restoring proper suction and priming in Pentair and compatible pool pumps.
How to Prime a Pool Pump the Right Way
Here’s a quick step-by-step checklist:
- Turn off the power to the pump.
- Remove the pump lid and fill the basket with clean water.
- Check the pump lid o-ring and seal it securely.
- Set diverter valves to fully open the skimmer line.
- Turn on the pump and watch for steady water movement in the lid.
- If it doesn’t catch prime in 2 minutes, shut off and repeat.
Signs Your Pump Is Primed Correctly
- Water is visible in the pump basket with no air gaps.
- You hear a steady motor sound without sputtering.
- Return jets in the pool are strong and bubble-free.
- The pressure gauge on your filter rises to normal operating range.
Conclusion: Get the Flow Back Fast
A pool pump that won’t prime can stall your entire system. Whether it’s air in the lines, low water level, or a clogged impeller, solving priming problems is often simpler than it seems. With the steps and products above, you can diagnose and fix the issue quickly—and keep your pool clean, circulating, and swim-ready all season long.
Still stuck? Use the checklist above or reach out to a local pool professional if you’ve tried everything. A properly primed pump is the key to a healthy, trouble-free pool.