Pentair IntelliFlo Pump Not Priming or Losing Prime (Air in the Basket)
- Suction-side air leak between the pump and the skimmer
- Dried or flattened pump-lid o-ring
- Loose lid or an unglued PVC joint
Problem Description
The IntelliFlo will not pull water up to fill the strainer basket, throws a Priming Failure alarm, or primes and then loses prime with air building in the clear basket. On a variable speed pump this is a suction-side air problem almost every time, not a dead pump, so the fix is finding where air gets in.
Why This Happens in Real Homes
A variable-speed IntelliFlo that will not prime is a suction-side air problem almost every time, not a dead pump. On real equipment pads the top two causes are a dried-out pump-lid o-ring and an air leak at a union or an unglued joint between the pump and the skimmer.
Fill the basket to force a prime, lube and seat the lid o-ring, and set the water level right, then hunt the leak by watching for bubbles at the returns before assuming the impeller or shaft seal has failed.
Symptoms
- Pump runs but the strainer basket will not fill with water
- Priming Failure alarm on the drive
- Basket fills but air keeps returning
- Pump primes then loses prime overnight
- Bubbles blowing back into the pool from the returns
- Weak or no flow at the returns
- Water level dropping in the basket while running
- Pump loud and cavitating from air
Recognize these? Here's what usually causes it.
Common Causes
- Suction-side air leak between the pump and the skimmer
- Dried or flattened pump-lid o-ring
- Loose lid or an unglued PVC joint
- Low pool water below the skimmer mouth
- Clogged skimmer or pump basket
- Priming settings too short for a long suction run
- Partly clogged impeller
- Failed shaft seal drawing air
Most fixes happen in the first 3 steps.
Turn the pump off at the breaker before removing the lid or working on the plumbing. Never run the pump dry while chasing a prime, since that overheats and can crack the housing.
Step-by-Step Solution
Fill the strainer basket and force a prime
Open the pump lid, fill the strainer pot with water right to the top, refit the lid, and restart so the pump has a water column to grab. A dry basket cannot self-prime, especially right after you have opened the filter or basket. If it fills and then holds prime, you simply lost the water column; if air keeps coming back into the basket, there is a leak to track down in the next steps.
Seal the pump lid and lube the o-ring
The clear lid on top of the strainer pot is the most common air leak on these pumps. Take it off, clean the o-ring and the seat it sits in, wipe a thin film of silicone pool lube, not petroleum grease, around the o-ring, and hand-tighten the lid evenly. Check the basket drain plugs are snug too. A lid that looks closed but has a dried, flattened o-ring pulls air the moment the pump spins up.
Set the water level and clear the skimmer
The pool water has to sit between half and two-thirds up the skimmer opening; any lower and the skimmer gulps air instead of water. Empty the skimmer basket and the pump basket of leaves, because a clogged basket starves flow and looks exactly like a priming failure. Confirm the skimmer weir flap is not stuck shut, which chokes the suction line.
Hunt the suction-side air leak
Air getting in anywhere between the pump and the skimmer stops the pump from priming. With the pump running, watch the pool returns for a steady stream of bubbles, and inspect the pump unions, the suction valve, and the PVC joints for a hairline gap or a joint that was never properly glued. Smearing a little pool lube or shaving cream over a suspect joint and watching it get sucked in confirms exactly where the leak is.
Tune the priming settings
In the IntelliFlo menu the priming range is adjustable from 1 to 10, with a default of 5, where a smaller number makes the pump move more water before it accepts that it is primed. If a healthy pump keeps alarming Priming Failure on a deep or long suction run, increase the prime time or adjust the range per the manual so it has enough time to catch prime before the alarm cuts in.
Check the impeller and shaft seal, then escalate
A partly clogged impeller or a failed shaft seal leaks air and prevents a solid prime. Reach into the basket housing and clear the impeller vanes of debris. If the basket fills but the pump still cannot build flow, or you see water weeping from under the motor where the shaft seal sits, that needs service. A Pentair dealer can pressure-test the suction lines to pinpoint a buried leak.
Quick Solutions
Still having issues? This is usually the deeper cause below.
If this comes back after following these steps, check whether a recent app or firmware update reset a default setting — the fix works, but the setting gets reverted silently.
Loss of prime overnight on a system that primes fine when running usually means a slow suction-side leak that only shows when the pump is off and water drains back, so check unions and the suction valve first. Pentair documents the IntelliFlo priming failure alarm in the pump manual and at partners.pentair.com.
This issue almost always looks more complex than it is — the majority of cases trace back to a single setting, a stale credential, or a default that shipped wrong.
- Suction-side air leak between the pump and the skimmer
- Dried or flattened pump-lid o-ring
- Loose lid or an unglued PVC joint
- Low pool water below the skimmer mouth
- Clogged skimmer or pump basket
Before you go — try one of these (they fix most cases).
Official Manufacturer Manual
Pentair provides official product documentation through their online manual rather than downloadable PDF. Access setup guides, troubleshooting steps, and product specifications for your Pentair IntelliFlo Variable Speed Pump.
Source: pentair.com
Need More Help? Pentair Support
Note: The contact information below connects you directly to Pentair's official customer support team, not Trunetto. They can help with warranty claims, device replacements, and advanced technical issues.