How To Determine Why a Pool Pump Won't Prime

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This guide will explain how to troubleshoot a pool pump that is not priming. The most common causes of pool pump priming issues are sucking air leaks in your pump housing or plumbing and debris clogs. For this guide, we’ll focus mainly on the suction side of your pool equipment. The suction side includes all equipment and plumbing, from your skimmers and main drains to your pool pump’s impeller. Priming a pool pump is crucial for the efficiency of the entire pool system, especially at the beginning of the pool season or after any maintenance that introduces air into the system, to ensure optimal performance and prevent damage.

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Video

Step by Step

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Step 1

Low Water Level - The pool water level should be kept about halfway up the skimmer weir door; maintaining this water level allows enough water through during ebbs and flows to prevent the skimmer from gulping air. 

How to Identify and Correct Air Leaks

Step 2

Missing Skimmer Basket - A missing skimmer basket will introduce any debris captured by the skimmer into your pool's plumbing line. The debris can build up to become a clog.

Related Article - How to Unclog a Pool Skimmer

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Step 3

Clogged Pump and/or Skimmer Baskets - An overfilled strainer basket restricts water flow, which makes priming more difficult. Cleaning your strainer baskets regularly, or at least make a habit of inspecting them weekly.

Related Articles - How To Clean Out the Pool Pump Strainer

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Step 4

Air Leak - Pump Lid and Pump Lid Gasket - Remove the pump lid from the strainer housing to check for warping, cracks, or issues with its thread (for screw-on lids only.)

Remove the lid gasket from its groove and check for signs of aging (cracking rubber) or pinches. An easy way to determine if your gasket is past its usefulness is to rub your fingers along it; if a black rubber streak rubs off on your hand, it’s time to replace the gasket. Additionally, inspect the pump housing or motor basket for air bubbles, as their presence can indicate an air leak, which is a common issue when the pump is not fully primed.

Quick Tip: Check for gasket deterioration by running your fingers along its length. If your gasket’s rubber has started to degrade, you’ll see heavy black smudges on your hand.

Related Articles - How to Identify and Correct Air Leaks

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Step 5

Adjust Diverter Valve Settings - Make sure that at least one suction and one pressure (return) line are open to allow water to pass through your system freely. 

Quick Tip: if not already, take this time to label your diverter valve ports; labeling will help prevent diverter issues in the future. Valves can be marked using homemade laminated labels.

Related Articles - How To Install a Diverter Valve on the Suction Side of a Pool


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Step 6

Air Leaks - Glued Joints - Small air channels can form in glued plumbing joints; these cracks can form due to age or soon after initial installation if glue is not thoroughly applied.

To identify problem joints, look for water spouts that pop up when the pump is turned off. Backpressure will force the water to backwash to the pool when the pump is turned off. The backflushing water will force its way through the cracked glue, indicating where to inspect next.

Related Articles - How to Test for Suction Side Air Leaks

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Step 7

Threaded Fittings - Use any techniques mentioned in the "How to Test for Suction Side Air leaks guides to find the leak. Once found, disassemble the joint union or adapter, and then apply 2 to 3 turns of Teflon tape to the threads. Before applying new tape, remove any bits of old tape or dirt from the threads.

Related Articles - How to Test for Suction Side Air Leaks

Step 8

Clogged Impeller - Impeller vanes can become clogged with mud, pine needles, or bulky debris. As the impeller gets more congested, the lower the pump's flow rate will drop. A precursor to priming issues is a drop in return jet flow rate.

Related Articles - How To Clean Out a Pool Pump Impeller

Step 9

Pump Speed Set Too Low - If your priming issue started after installing a dual-speed or variable-speed pump, the priming speed may be set too low for your system. Reference your pump's owner manual for instructions on how to reset the initial priming speed.

Related Articles - Best Setup For Variable Speed Pool Pumps 

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Comments

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(121 to 160 of 181)

 Posted: 3/21/2017 

I connected a manual cleaner while the pump was working, it immediately lower the pressure due to the air in the hose. After that the pump hasn't been able to prime. Did I mess up the pump?
 Reply

InyoPools Product Specialist  Posted: 3/20/2017 

Paul – You should see a part number on the underside of the cover. Put that into our customer page and it will point you to a parts list for this pump.
 Reply

InyoPools Product Specialist  Posted: 3/20/2017 

FlaPool - Sounds like you may have a clog in your skimmer/vacuum line. Try blowing the clog out with a drain cleaner bladder. It's simple, cheap and most people have had good success with them. It’s most effective if you insert it at the pump going back to the pool. Shut off the main drain before attempting to blow the skimmer/vacuum line out. Any hardware store sells these bladders.
 Reply

 Posted: 3/19/2017 

My pump basket lid has a flattened O-ring so pump will not prime. Where can I get new O-ring? Inside diameter of O-ring is 5 inches; outside is 5 1/2 inches, or very closely those values.
 Reply

 Posted: 3/16/2017 

Skimmer/Vacuum stopped working "all of the sudden" - will not prime. Main Drain is fine and flows extremely well. Open skimmer/vacuum line - flow stops. Close that line, flows again fine. What is going on?
 Reply

InyoPools Product Specialist  Posted: 3/6/2017 

tw - Try pulling the motor out of the pump to check the impeller more closely for debris. Then try filling the strainer basket with water again to fill pipes that may have completely drained. Re-check the rest of the steps in this guide. I assume you haven't had a hard freeze that may have broken something on the suction side of the pump.
 Reply

 Posted: 3/5/2017 

I have a 30,000 gallon inground pool. I replaced the pump a couple of months ago which I purchased from INYO pools. It worked like a charm. I have turned it off a couple of different times this winter for a month at a time to save on the energy bill. It reprimed each time until now and I can't get it reprime now. Nothing has seemed to changed. I have check the impeller, seals look good, all baskets clean. Just don't understand why it will not work now.
 Reply

InyoPools Product Specialist  Posted: 2/17/2017 

Kingy70 - You new pump may be underpowered. Did you replace the old pump with a smaller pump? Did you replace the pump with an equivalent pump? Look at the Total HP (THP) of each pump. The product of the listed HP and the Service Factor (SF) - both on the motor label - will give you the respective THP. These products must be the same to have an equivalent pump. Lastly, do you have a working check valve between the pump and the solar panels? This valve will keep the water in the solar pipes and panels from emptying when you shut the pump off causing the pump to refill the solar system on startup.
 Reply

 Posted: 2/15/2017 

just changed my solar heater pump. Pump now takes forever to get enough flow through to get the water circulating. When it does there is not enough flow to ensure the system is operating at maximum. it sounds like the water is just trickling down the return pipe. How do I get the air out of the lines to ensure max flow?
 Reply

InyoPools Product Specialist  Posted: 12/12/2016 

Eric - Since the only change you made to your system was to add the heat pump, I would concentrate on it. Sounds like the heat pump was not installed correctly. You should not have seen the PSI increase. The heat pump should not make that much noise. And the pump should not prime slower that before you added the heat pump. I would have the heat pump installer come back and check the heat pump installation.
 Reply

 Posted: 12/6/2016 

#1: I just had a heat pump installed on my pool. Pryor to the install my filter had a 12-16 PSI. After the install my filter is at 25-29 PSI. The spider valve is 1 1/2" enlarging to 2" about 2' away. Heat pump is about 10 from filter. Is the PSI increase normal?
#2: The water going through the heat pump is very noise (louder than the pool pump. Is this normal?
#3: One jet at the pool has constant air coming from it and the strainer basket doesn't hold a good prime (take 15 to 20 seconds to prime after being shut off). Any suggestions other than changing out the skimmer lid gasket and the gasket connecting the pump and skimmer?

 Reply

InyoPools Product Specialist  Posted: 11/5/2016 

Rerun - Make sure your VS pump is starting up in high speed to get the suction required to prime the pump. If that's not the issue, you might consider adding a check valve between the pump and the pool so the water doesn't flow backward into the pool when the pump is off.
 Reply

 Posted: 11/5/2016 

Just purchased a new Hayward MaxFlow variable speed pump. I had to re-orientate the inflow pipes to fit. Pump initiated a self prime and worked fine - pressure was strong and no apparent leaks. The next day pump turned on but there was now water inflow. I stopped the pump - pulled the skimmer basket and manually filled with water. Pump primed and works fine. However, this happened again the following day and repeated. Need help as I can't keep having to manually prime the pump each time.
 Reply

InyoPools Product Specialist  Posted: 11/4/2016 

Jose - One of the most common problems for low pressure is a clogged impeller. See our guide on "How To Clean Out a Pool Pump Impeller" for a simple fix. If that doesn't solve your problem, see our guide on "How To Determine the Cause of Low Water Flow".
 Reply

 Posted: 11/3/2016 

Hi,
I have a problem with my system. It was running smoothly until two days ago, and nothing out of the ordinary was done.The water is circulating but my cleaner is not moving due to low pressure. I have taken all the pipes out and placed my hand over the hole in the wier (where pipes connect) and very ow pressure. Water flows nearly 100% out of the jet. The baskets are all clean, the impeller seems to be clear (it moves freely when i rotate it with my hand). There is no noise coming from any of the pipes that run from the cleaner to the wier. The water level is also correct.

 Reply

InyoPools Product Specialist  Posted: 7/30/2016 

peter78312 - If you can run one or the other function at a lower speed, it might save you money to split them out. You may have to run the slower function longer to filter all your water.
 Reply

Anonymous  Posted: 7/28/2016 

Thanks for the help. I re did the piping on both sides of the filter and it fixed the prime. I think the last time i cleaned the impeller I must have jarred a connection and created some air in the line. fixed now.

One last question i have a 3 way jandy valve that comes from the filter and splits back to the pool sweep pump on one side and the other to the solar pre heat. It has a electronic valve actuator. During the day when i am both filtering the pool and running the pool sweep should i seperate out the function? meaning the first 2 hours are sweeping the pool and the 2nd 2-3 hours are pumping water thru the solar pre heat?

Thanks again for your help. It has helped immensely.

 Reply

InyoPools Product Specialist  Posted: 7/25/2016 

peter78312 - If your pump won't prime when the filter is in the Recirculate setting, your problem is not in your filter. Recirculate bypasses the filter - water comes in from the pump and is immediately diverted back to the pool without going through the filter. Assuming you have an in-ground pool, is your new pump an in-ground pump. An above ground pump will not be able to suck the water from the pool to the pump. Check also that your pump's impeller is not clogged with debris. As far as having too much sand in the filter, that should not affect priming, but it may affect backwashing when your system is up and running. You should have 6" to 12" of space between the sand and the top of the tank depending on the filter model.
 Reply

Anonymous  Posted: 7/23/2016 

Thanks for the response. So i replaced the sand, replaced the jandy valve, replaced the lateral assembly and it still wont prime in either recirculate or filter mode. I followed the instructions on the way to fill the sand filter and i have 500 lbs of sand in there give or take a few lbs maybe. Could too much sand cause the pump to not function? does it just take a while to get the laterals circulating after filling the sand?
 Reply

InyoPools Product Specialist  Posted: 7/15/2016 

Peter78312 - See if your pump primes in Recirculate mode. If it does, you have a filter issue. If you haven't changed the sand in 5 years or so, you might try that. Check the spider gasket in your multiport valve to make sure it is not damaged. Check that your pump powers up in high RPMs and then drop back to a lower level after it has primed.
 Reply

 Posted: 7/14/2016 

I have a new intelligence variable speed pump and I can prime the pump when I am back washing the Hayward jandy sand filter but but when I switch to filter I can't get the pump to prime. I am confused as to what is happening here.

Thanks.

 Reply

InyoPools Product Specialist  Posted: 7/5/2016 

grace - It sounds like you are getting air through the skimmer when you are vacuuming. Make sure your skimmer basket has enough water in it to cover the hose connections. Also, your may have holes in your cleaner hoses or connections. Hold the cleaner hose under water while the pump is on to see if the pump primes. If it does, sequentially lift each section of the hose above the water surface to see when you lose prime.
 Reply

 Posted: 7/1/2016 

I'm trying to vacuum the pool (new at this). Vacuuming to waste with main drain closed and skimmer open. I can't get the pump to prime when I have it on waste, so no suction. It primes just fine when it's on filter setting. just had the sand changed in the filter, could that cause this problem?
 Reply

InyoPools Product Specialist  Posted: 6/27/2016 

mamdturner - You may have a small crack on the strainer cover. Try running the garden hose over the strainer cover while you are priming the pump. If your pump primes, inspect the cover and the strainer groove for cracks. To detect air leaks around the suction pipe connections, try smearing shaving cream around each connection. Air leaks will show up as pot holes in the shaving cream.
 Reply

 Posted: 6/25/2016 

I have a Hayward TriStar pool pump for a water feature. The water feature stopped working. The pump will not hold a prime. The pump motor runs. The impeller is functioning properly. All screens and skimmer baskets are clear. I replaced the Strainer Cover O-Ring. Still no prime. I ran a water hose to fill up the Strainer Basket. The basket never filled up as water ran out the inflow pipe and never filled up after ten minutes. There are no detectable leaks. Am I missing something?
 Reply

InyoPools Product Specialist  Posted: 6/24/2016 

Jason - unfortunately, we don't sell these pumps but from what you describe, you may have a bad "new" pump. That happens occasionally. These above ground pumps are gravity feed so they should not have a problem priming. You might take it apart and see if the impeller is connected or clogged.
 Reply

 Posted: 6/22/2016 

Hello. Just recently purchased a Bestway 2500gl pump for my above ground pool. After connecting the lines, I bled the air valves in the pump and ensured all lines were open. I turned the new pump on for the first time and the motor was running but there was no circulation of water. I am assuming the pump was not primed properly. After a few unsuccessful attempts, I disconnected the new pump and used an older one that was hooked up before the new pump arrived. The old pump fired right up and works great. This leads me to assume that there is no problem with the lines, but it lies with the pump. I have used these type of pumps for many years now, and would like to think I have the new pump hooked up properly and bled accordingly, but something is off. Any suggestions would be appreciated.
Here is a link to the new pump(rural king link): http://www.ruralking.com/intex-filter-pump-2500-gallon-per-hour-56633e.html


 Reply

InyoPools Product Specialist  Posted: 6/6/2016 

pool lover - If your motor just hums and doesn't start up, it probably has a bad start capacitor that needs to be replaced. See our guide on "How To Replace a Pool Pump Capacitor".
 Reply

 Posted: 6/5/2016 

we just put in our pump today and are having a realy hard time trying to get it to work. when we turn it on it hums as says it works but no water is being filtered. we tryed again and again and nothing is working, it also says low water flow. like i said no water is actual being pushed back in the pool. can somebody please help?
 Reply

InyoPools Product Specialist  Posted: 6/3/2016 

Chas - Is this a brand new system? Has it never been primed? I don't understand why the check valves don't keep the water from draining down into the pool when the system is off. If you have a check valve between the pump and the pool, it may have failed and may need to be replaced.
 Reply

InyoPools Product Specialist  Posted: 6/2/2016 

Mitch LV - If your pump was able to be primed from the pool in the past, it could be that you have something restricting water flow in your pool system. Two common areas are a clogged impeller and a clogged filter. If you have a cartridge filter, try priming the pump from the pool without the cartridge in place. If you have a sand or DE filter try running the filter in recirculate mode.
 Reply

 Posted: 6/2/2016 

I have an in ground pool with a pump system that is a good 6 feet up a hill. It has several check valves to prevent water from back flowing to the pool and this works during normal operation. But once I remove the lid from the pump strainer you can hear air rushing into the system and then no matter how fast or how much priming I do, it does not reprime. Need to know how I can stop this and best way re prime system with this configuration.
 Reply

 Posted: 6/1/2016 

My pump will only prime from the spa. After I get the pump going from the spa, I can switch it to the pool and it will continue to run. But, it won't generate enough suction just pulling from the pool to start. Any suggestions?
 Reply

InyoPools Product Specialist  Posted: 5/30/2016 

Zoe - The hum from your motor is generally one of two problems. The start capacitor may be bad of you may have a short in your pump windings where the motor gets hung up. To check the capacitor, see our guide on "How To Replace a Pool Pump Capacitor". If the windings are bad, you should consider getting a new motor.
 Reply

 Posted: 5/27/2016 

Hi, I have an above ground pool. We started the Hayward super pump/ self-priming ( about 4-5 years old) for the first time yesterday. Pool is 19X12. It took the pump a few minutes to start but then it run for 4 hours. I stopped it and today the pump won'tP start. There is a bit of hum at first, but very shortly there is no sound. Checked the breaker, the filter should be clean. Pool level in the pool a bit high. I opened the Strainer basket in the pump- lots of water came out as it is hooked to the pool but I think it is fine. Skimmer basket is clean. I even opened the pump and made sure the shaft is turning. There is a lot of corrosion but its turning. And it worked already for 4 hours yesterday. It seems as something else is interfering. what do you think I should do? Thank you!
 Reply

InyoPools Product Specialist  Posted: 5/20/2016 

Jeff - If you have an above ground pool, the short hose between the filter and the pump is generally secured to the pump fitting with a hose clamp. If you have an in-ground pool with rigid pipe, that connection is glued on.
 Reply

 Posted: 5/19/2016 

Great article. I have a Hayward DE filter. First time opening up the pool my self and no water was initially circulating though the pump. I then primed the pump but now water is coming out the the pipe the connects to the pump to the filter. the end of the pipe isn't not attached it easily slips out if i pull it upward. is it broken or do i just need to glue it
 Reply

InyoPools Product Specialist  Posted: 5/16/2016 

Dr. Randi - Check your pool's water level to make sure it is halfway up the skimmer opening. Also, check that nothing is jamming the door at the skimmer opening. Then check to see if debris is clogging your pump's impeller. See our guide on "How To Clean Out a Pool Pump Impeller".
 Reply

 Posted: 5/16/2016 

I opened my pool filed the strainer basket with water, ever replaced the gasket and when starting the pump the water in the strainer sucks down to 1/2 and just wont fill up to get the pump running with pressure so the water never begins to circulate to the pool.
Any suggestions?

 Reply

InyoPools Product Specialist  Posted: 5/4/2016 

Geronimo - It sounds like you have a major air leak on the suction side of your pump. First, check the O-ring under your pump strainer cover. If it's stretched out or damaged, it may need to be replaced. Then, check the cover itself for cracks. If no solution there, see our guide on "How to Identify and Correct Air Leaks" for other possible options.
 Reply