Jandy VS FloPro or ePump Not Priming or Losing Prime
- Dried or cracked lid o-ring
- Debris in the o-ring seat holding the lid open
- Air leak at the union o-rings
Problem Description
The Jandy pump runs but will not pull water up into the strainer, or it primes and then loses prime with air collecting in the housing. On the FloPro and ePump the culprit is nearly always the lid o-ring or a suction-side air leak rather than the motor, so the job is sealing the suction side.
Why This Happens in Real Homes
On a FloPro or ePump the culprit is nearly always the lid o-ring or a suction-side air leak rather than the motor. On real equipment pads the o-ring is the number one air leak, especially right after cleaning the basket, and on the ePump grit in the o-ring groove holds the lid open a hair and pulls air the whole time it runs.
Fill the housing, clean and lube the o-ring, and check the union o-rings before chasing buried leaks or opening up the pump.
Symptoms
- Pump runs but will not pull water into the strainer
- Primes then loses prime with air in the housing
- Air collecting at the top of the strainer
- Bubbles blowing into the pool from the returns
- Weak or no flow after the pump runs
- Loses prime overnight
- Basket water level drops while running
- Pump noisy from trapped air
Recognize these? Here's what usually causes it.
Common Causes
- Dried or cracked lid o-ring
- Debris in the o-ring seat holding the lid open
- Air leak at the union o-rings
- Low pool water below the skimmer
- Clogged skimmer or pump basket
- Unglued or loose suction-side PVC joint
- Clogged impeller or cracked diffuser
- Failed shaft seal
Most fixes happen in the first 3 steps.
Shut the pump off at the breaker before opening the lid or loosening unions. Do not run the pump dry while trying to prime it, as that overheats the seal and housing.
Step-by-Step Solution
Fill the strainer housing before starting
Open the pump and fill the strainer housing with water to the top, then refit the lid and start the pump so it has a water column to prime from. A pump started dry right after you cleaned the basket will spin without ever grabbing water. If it primes now and stays primed you only lost the water column, but if air comes back into the housing, work through the seals below to find where it enters.
Inspect and lube the lid o-ring
The FloPro and ePump lid o-ring is the number one air leak on these pumps. Remove the lid, check the o-ring for cracks and flat spots, clear any grit sitting in the o-ring seat, and reseat it with a thin film of silicone pool lube. On the ePump especially, debris in the o-ring groove holds the lid open by a hair and pulls air the whole time the pump runs. Hand-tighten the lid evenly, without tools.
Set the water level and clear the baskets
Keep the pool water at least halfway up the skimmer opening so the skimmer is not gulping air, and empty both the skimmer basket and the pump strainer basket. A basket packed with leaves cuts flow enough to look like a priming failure even when every seal is fine, so rule this out before opening up the plumbing.
Check the union o-rings at the pump
The pump joins the plumbing with union nuts on each side, and their o-rings are a frequent air leak on Jandy pumps. Loosen both unions, slide the pump aside, remove and clean both union o-rings, then reinstall them and hand-tighten the union nuts back onto the pump. Clean, properly seated union o-rings should seal by hand, so do not overtighten to try to stop a leak, which distorts the o-ring instead.
Find the suction-side leak
If air still builds up, it is entering somewhere between the pump and the skimmer. With the pump running, watch the pool returns for bubbles blowing in, and check the suction valve stem, the drain plugs, and the PVC joints for a gap. A joint that was never fully glued pulls air steadily and never lets the pump hold prime, and it often only shows once the pump has been running a minute or two.
Inspect impeller, diffuser, and shaft seal, then escalate
Reach through the basket housing and clear the impeller vanes of debris, since a clogged impeller or a cracked diffuser leaks air and kills prime. Water weeping from under the motor points to a failed shaft seal. If the housing is full, the o-rings are good, and it still will not build flow, have a technician pressure-test the suction lines and inspect the impeller, diffuser, and seal.
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.
If the pump lost prime only after you serviced the filter or basket, the lid o-ring is nearly always the cause, so start there before chasing buried leaks. Jandy pump manuals and the FloPro and ePump troubleshooting steps are on jandy.com. Keep a spare lid o-ring on hand, since a season of pool chemicals hardens them.
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.
- Dried or cracked lid o-ring
- Debris in the o-ring seat holding the lid open
- Air leak at the union o-rings
- Low pool water below the skimmer
- Clogged skimmer or pump basket
Before you go — try one of these (they fix most cases).
Official Manufacturer Manual
Jandy provides official product documentation through their online manual rather than downloadable PDF. Access setup guides, troubleshooting steps, and product specifications for your Jandy Variable Speed Pool Pump.
Source: jandy.com
Need More Help? Jandy Support
Note: The contact information below connects you directly to Jandy's official customer support team, not Trunetto. They can help with warranty claims, device replacements, and advanced technical issues.