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 154)

 Posted: 10/20/2019 

New pool.owners here Every time we clean the filters we have an issue w priming from full pool suction. If I adjust to partial spa suction it gets it moving but from full pool it causes dry prime alarm to sound. Any suggestions?
 Reply

InyoPools Product Specialist  Posted: 10/21/2019 

Your water level may be too low, which allows the pump to gulp air. You can also still check the plumbing elements we mention in the guide to determine if they may be causing the air in the system, i.e., valves, unions, joint adapters.
 Reply

 Posted: 10/15/2019 

just changed my old 1 speed to a variable speed ECM27SQU. After 1 full day of operation, here are my results : 2h at 3450 pump is primed at 98% (small size air bubble); 2h at 2600 pump does not quite prime (air bubbles in most of the lid); 8h at 1725 and there is little/no priming (about 4-5" of water in the basket; almost no pressure at the filter meter reading, but water circulates). Also at 3450, my inline cleaner was working, but once it dropped to 2600 (and of course to 1725) the cleaner stopped working; i then closed the cleaner valve hoping to suck more water out of skimmer and main, but that did not change much; pump was still not priming anymore. I then did the soap water test and could not find a leak around any fitting or valve or lid. Water is about 1/2 way to the skimmer. What should i do or look for next ?
 Reply

InyoPools Product Specialist  Posted: 11/4/2019 

So with a variable speed motor you may not see a pump with a full prime as the suction has decreased. When the RPM's are lower and the suction is lower, your cleaner potentially not having enough suction is normal. Not all pool systems will generate enough suction and water pressure in the lower RPM's. Each swimming pool is different however after testing the settings, not having any air suction leaks and seeing water flow back to the swimming pool in at least some of the lower RPM's you do not have to be concerned. 
 Reply

 Posted: 9/4/2019 

My pump looses suction within a minute whenever I connect the hose to vacuum the pool. The pump runs 6 hrs every night with no problems. As soon as the hose goes on the skimmer box cover , the pump noise changes as if cavitating . I bought a brand new hose and still the same. Tried a new vacuum head also , as old one warping . I replaced the 8 yr old pump with the same ( Davey Silensor ) because it had a broken impeller when I opened it up to investigate. I am baffled as there is no obstruction. Has anyone got any idea ?
 Reply

InyoPools Product Specialist  Posted: 9/4/2019 

Hello David - Do you have an above ground or inground pool?
 Reply

 Posted: 9/4/2019 

I have a 55,000 litre concrete in ground pool that is 25 yrs old.
 Reply

InyoPools Product Specialist  Posted: 9/5/2019 

The pump is not receiving enough water when the hose is plugged into the skimmer. Try opening up the main drain more so that it can pull additional water.
 Reply

 Posted: 8/7/2019 

I think he went through everything and i had 3 things that he mentioned was the problem
 Reply

 Posted: 8/2/2019 

This guide is awesome. Thank you for making it.
 Reply

Anonymous  Posted: 7/7/2019 

I cant get my filter to prime. I sit there and fill the water for 5 minutes or more and it never fills all the way up. After I turn it on it immediately drains from the filter and starts sucking air. I tried all methods above. Please help.
 Reply

InyoPools Product Specialist  Posted: 7/8/2019 

This is a more thorough guide on How to Identify and Correct Air Leaks. If you still can't find the issue after following the guide then you may want to try calling a professional to take a look. 
 Reply

 Posted: 6/19/2019 

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 

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?
 Reply

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?
 Reply

 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).
 Reply

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