How To Determine Why a Pool Pump Won't Prime

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This guide discusses the common problems involved with a motor that won't prime. Most priming problems involve leaks in the suction side of the pump (between the pump and the pool) or clogged baskets. If you have a leak on the pressurer side (after the pump), it does not affect prime. You just lose water.

Video

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Step 1

Pool level too low - If the pool water level is below the mid-level of the skimmer opening, there is a chance of sucking air into the circulation system through the skimmer. Enough air is the system will cause your pool pump to loose prime.

Step 2

No water in Strainer basket - Open the strainer cover and fill the strainer basket and supply lines with water for 2-3 minutes. Reseal the strainer cover.

Step 3

Skimmer basket clogged - Remove the skimmer basket and clean debris out with a hose.

Step 4

Strainer basket clogged - Remove the strainer basket and clean debris out with a hose.

Step 5

Strainer basket cover leaking - Remove the cover on your strainer basket cover. Then remove the gasket generally in a groove around the top of the strainer basket. Check that it is not cracked or has worn spots. This gasket is a common problem and should be replaced periodically. Replace the gasket in its groove and lubricate it lightly with a silicon based lubricant. Do not use Vaseline. Close the cover and hand tighten. Do not over-tighten with a tool.

Step 6

Suction or discharge valves closed - Make sure that at least one suction and one discharge valve is open so that you have a path open for the water to flow. See our guide on "How To Install a Diverter Valve on the Suction Side of a Pool" for further information.

Step 7

Leaks in glued fittings - Check for leaks in the glued fittings on the suction side of the pump. Sometimes the glue is not spread all around the pipe and you will get small air channels in the glue. Occassionally when you turn off the pump the backpressure will squirt water out this hole. In normal operation, air is being sucked into this hole. If you don't see water squirting out, turn the pump back on and drip some water around the pipe fitting joint. If you see the water getting sucked in, you have a hole. Redo the connection. See our guide on "How To Glue Pool Fixtures Together" for more instructions.

Step 8

Leaks in threaded fittings - If you have threaded fitting on the suction side of the pump, you may have a suction leak there. Try the water drip test above. If you find a leak, take the fitting apart and wrap the threaded fitting with 4-5 layers of plumbing tape. You may have to cut the other end of the pipe and re-glue it to get the threaded pipe out. See our guide on "How To Glue Pool Fixtures Together" for more instructions.

Step 9

Leaks at unions on suction side - Check for leaks around the glued connection of the unions as above. Then take the union apart and check that the O-ring is good and is seated correctly. Lubricate the O-ring with a silicon based lubricant. Rewrap the threaded side of the union with 4-5 layers of plumber's trape and hand tighten the union back together.

Step 10

Impeller is clogged - If the pump's impeller is clogged with debris, water will not be able to flow out the side slots and generate a vacuum. Without a vacuum, the pump will not be able to suck water into the pump and it will not prime. Remove the impeller and clean out the debris. See our guides on "How To Clean Out a Pool Pump Impeller" and "How To Replace A Pool Pump Impeller" for more information.

Step 11

2-Speed pump starting at low speed - When you start a 2-speed motor, it generally has to be started at high speed to created enough suction to prime the motor. After it is primed, the motor can be shifted down to low speed.

Comments

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(1 to 40 of 142)

 Posted: 6/19/2019  Latest

I have a pump that will prime but loses it when the filter basket is almost full. At that point the water in the basket area drains away and I can see the water coming from the pool to start filling for prime. It just repeats that cycle and never runs in normal filter mode (or backwash for that matter). Any thoughts? Thx in advance Scott
 Reply

InyoPools Product Specialist  Posted: 6/20/2019  Latest

It sounds like you have a sucking air leak. Have you checked any of the things mentioned in the guide? How to Identify and Correct Air Leaks
 Reply

 Posted: 6/2/2019 

Pump not getting enough water to return
 Reply

InyoPools Product Specialist  Posted: 6/6/2019 

Have you done any of the steps mentioned in the guide?
 Reply

 Posted: 5/23/2019 

My pump keeps losing water and stays about half full. There is strong suction at the skimmer and the return seems normal strength but with alot of bubbles. My PSI gauge is reading zero, no movement no mater what I do. Thoughts?
 Reply

InyoPools Product Specialist  Posted: 5/23/2019 

Hello Eric - My guess is that you have a suction side air leak. Check out our guide titled "How to Identify and Correct Air Leaks".
 Reply

 Posted: 5/19/2019 

My 1hp Hayward pump died. I replaced it with a variable speed 1.5 hp Blue Torrent pump. Pool is 11000 gal. This pump came with a 1.5 inch inlet and outlet instead a 2 inch that I had. So I reduced at the pump. I can't get pump to prime most of time. I've tried the airleak tests and don't notice any . If I do get it working. I gave quite a few air bubbles in return. Also I can only lower the speed to 2400 rpm. Any lower and it won't stay primed. Even at 2400 it's only filling basket about 3/4 to the way. Is it a poor pump or do I have air leaks. My old pump would lose prime sometimes. I can only get it to stay primed if I run vac and skimmer at same time. If I try to use just one or the other it loses prime
 Reply

InyoPools Product Specialist  Posted: 5/20/2019 

The priming issues are likely caused by switching to a less powerful pump. Brands like BlueTorrent make entry level pumps, and their flow rates are on the lower end of the spectrum no matter the HP. For example, you went from a Super II to a BlueTorrent; there could be a difference of 20 gallons per minute in flow rate depending on the system.
 Reply

 Posted: 5/17/2019 

Thank you SO much. I had been trying to prime my pump for the last 24 hours but nothing would work. After watching your video, it took me 2 minutes. The washer had fallen off of my pump lid and I hadn’t noticed. It wasn’t much but it wouldn’t work. Something so simple. Thanks!!!
 Reply

InyoPools Product Specialist  Posted: 5/17/2019 

That's great, Hélène. Thank you for the feedback.
 Reply

 Posted: 5/2/2019 

Pump won’t suck water from pool. I can open the basket cover next to the pump and put a garden hose in there and water will circulate out the jets. I can’t figure out what’s wrong. I’ve primed the pump. I’ve filled the lines. The filter is full. I’ve done this every spring for 7 years now and never had issues until now. Any suggestions?
 Reply

InyoPools Product Specialist  Posted: 5/3/2019 

Hello Kendall - Make sure the valve in front of the pump is set so that water can be pulled from the skimmer and main drain. These valves are typically closed when the pool is winterized.
 Reply

 Posted: 5/3/2019 

Thanks. It’s working. I have always drained the pump with that plug in the fall. And it was closed back right. As soon as I loosened it, the water started to circulate like it is supposed to. Thanks again!!
 Reply

 Posted: 5/2/2019 

Can a pump be primed with out the diffuser or do I need to wait for that part t o come in? Also tips for getting a stuck impeller bolt out?
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InyoPools Product Specialist  Posted: 5/6/2019 

The main job of the diffuser is to make priming possible. But your pump may be able to prime; but unfortunately, I have never attmpted a diffuser-less prime. What is the make and model of your impeller to better understand the best methods of removing the impeller?
 Reply

 Posted: 4/23/2019 

Changed my sand and replaced my pump and motor. Psi is high. Everything works fine with it in recirculate mode (psi is still high- 18 ish) but when i switch to filter i lose prime after 15ish minutes and its barely doing anything. Psi when in filter mode is like 24. Ideas?!?!
 Reply

 Posted: 4/24/2019 

The HP is the same. The water is green. Both skimmer baskets are empty. Filter has already been backwashed. Still happens after 15ish minutes.
 Reply

InyoPools Product Specialist  Posted: 4/24/2019 

You'd be surprised how fast a filter can fill up when the pool is green. We'd recommend killing the algae and backwashing the filter multiple times a day until the water is clear. At that point, it should operate normally.
 Reply

 Posted: 4/24/2019 

Would that cause the filter to lose prime within 15 minutes though?
 Reply

InyoPools Product Specialist  Posted: 4/24/2019 

Yes, it could happen that fast.
 Reply

InyoPools Product Specialist  Posted: 4/24/2019 

Hello Cody - Did you stay with the same HP when you changed the pump or did you increase the HP? Is the pool water clear or is it cloudy/green?
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 Posted: 4/23/2019 

i have been fill-in the simmer basket forever it seems like(my garden hose isn't long enough), and its not filling. what setting should the filter be on while doing this? i feel like I'm trying to drain the hot water out of a coffee maker (waitress joke).
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InyoPools Product Specialist  Posted: 4/24/2019 

Hello Jamie - the valve can be set on its regular filtering mode while filling the pump. How are your water levels? Is your water level about halfway up the skimmer door? If your water is below the skimmer, that might be your problem.
 Reply

 Posted: 4/20/2019 

I drained the pool pump last fall to winterize, then I realized that I needed to run it again briefly, but forgot to add water to the system. Within a few seconds, the skimmer chamber filled with smoke. The motor still runs, but it won't self-prime anymore. Is this repairable, perhaps by replacing the impeller, or do I need to replace the entire pool pump?
 Reply

InyoPools Product Specialist  Posted: 4/24/2019 

Unfortunately, this not something we can tell you for sure; You or a technician will have to inspect the pump for any damage. Test the motor to determine if it still runs. Open the pump to check for any damaged hardware or gaskets.
 Reply

 Posted: 3/29/2019 

Hi, I have sta rite pump P6RA6G-207L that is not priming, the water is circulating but in low pressure. I replaced the the o’rings, checked the impeller, the difusor. I even replace the fittings of the suction line. The pump is a single speed one but seems like it was working in a low speed. It has 2 capacitors. Is it possible one of those is damaged? I appreciate your help.
 Reply

InyoPools Product Specialist  Posted: 4/9/2019 

Hello Gilbert - there are a few things you can test: line voltage, run capacitor, and start capacitor. To test any of these, you will need a multimeter. Read the following guides on how to safely test these components: How To Use a Multimeter to Test a Pool Pump Motor - Voltage, How to Test a Pool Pump Capacitor
 Reply

 Posted: 3/29/2019 

I have the same problem as Lori. When running normally the pump doesn't prime all the way (there are bubbles at the top), but when I switch to backwash it immediately fiills completely. I have replaced o rings, made sure there weren't any leaks in the valves and the water level is correct. What else could it possibly be? Thank you.
 Reply

InyoPools Product Specialist  Posted: 3/29/2019 

Hello Tricia - What type of filter do you have? What is the PSI reading when the valve is set on filter mode?
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 Posted: 3/24/2019 

Pool pump wont prime all the way! I have replaced motor all pump seals and o rings. The basket will not fill completely , when I put it to backwash it fill the basket as soon as I put it back the water level starts to drop and basket as air bubbles. Cant seemed to find were air is getting in to system.! Any suggestion!! Over this pool about ready to fill in with dirt!!!
 Reply

InyoPools Product Specialist  Posted: 3/26/2019 

Hello Lori - Is the water level in the pool at least halfway up the skimmer door opening?
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 Posted: 7/13/2018 

Hello Beverly - Check out our article titled "Why Are My Pool Jets Not Working?". It covers several reasons why the system wouldn't be operating correctly.
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 Posted: 6/17/2018 

my pool filter system kept losing suction and the out put would virtually stop. so before i read your posts and such i checked the sand (not too dirty) checked the valve (a little stiff but workable) the pressure guage is off the grid . so i bought a new pump and i get the same result. the pump wont keep running so i'm backwashing every hour and a half or so to keep it moving, but it does not continue to circulate. HELP
 Reply

 Posted: 5/8/2018 

Hello Cory - Since every pool is different, diagnosing valve settings is tricky. You have to test the settings manually and see what works. I'm wondering if something is mislabeled because everything works when the skimmer is "closed". Is water pulling from the skimmer when the valve says it's closed?
 Reply

 Posted: 5/5/2018 

Just bought our home. Never had a pool, so had a service come out to do an initial evaluation and clean/chemistry check. They determined that the chlorine levels were ridiculously high and recommended draining pool about 2 feet and then refilling with fresh water. He turned off the skimmer, pump stayed on. Pump is on a timer. So, after draining, we began filling back up. This morning pool is back to normal level, we turned on the skimmer and then the pump. Pump wouldn't prime. We turned off the skimmer, pump primed and water feature and jets all operational. We then tried turning the skimmer back on and pump lost prime. Right now we are running just the pump with the skimmer turned off. Is there something we should know about this, is this normal? We are assuming this is not normal. Thank you for any help/advice!!!
 Reply

 Posted: 5/4/2018 

Hello Jeff - Have you tried opening up both the skimmer lines and drain at the same time? This will ensure that the pump is getting enough water. If it's still not priming, you may have a suction side air leak or a clog in one of the suction lines. Check out Part 1 of our article titled "Why are my pool Jets Not Working?". It has a lot of good info about correcting possible problems.
 Reply

 Posted: 5/4/2018 

Just recently had a new liner replacement, which means all water was removed from system. Once the liner was replaced, and pool filled to middle of skimmer I went to go start it up. I cannot get the pump primed. When set to skimmers only seems like just a little water comes out the pipes, when set to main drain it seems I can keep filling and filling the pipes. First year this has happened. Thanks in advance.
 Reply

 Posted: 3/21/2018 

Hello Sarah - What is the pressure reading on the filter gauge when the valve is in the filter position?
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 Posted: 3/21/2018 

Hello Beldor - Hopefully, the impeller and diffuser weren't altered in any way. That is a common issue when the pumps run dry and then won't prime. How does the pump lid o-ring look? If it is cracked or leaves black marks on your hand, I would replace it.
 Reply

 Posted: 3/21/2018 

Hello RG - Check the cleaner hoses for holes. Holes in the hoses are a very common cause of air bubbles. Are you seeing air bubbles in the returns? If so, you have a suction side air leak. Besides the hoses, it could be from your pump lid o-ring, pump drain plugs, intake fitting, or your diverter valves. If there are no bubbles in the returns, the pump is cavitating and causing vapor bubbles. If this is the case, you'd have to feed the pump more water by opening up the skimmer or main drain.
 Reply