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. We’ll be focusing mainly on the suction-side of your pool equipment for this guide. The suction-side s all equipment and plumbing from your skimmers and main drains to your pool pump’s impeller.

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Step by Step


Step 1

Low Water Level - The pool water level should be kept at 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 checks for signs of aging (cracking rubber) or pinches. An easy way to determine if your gasket is past its usefulness, rub your fingers along the gasket; if a black rubber streak rubs off on your hand, it’s time to replace the gasket.

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 freely pass through your system. 

Quick Tip: if not already, take this time to label your diverter valve ports; labeling will help prevent diverter issues in the future. Calves 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 was not thoroughly applied.

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

Related Articles - How to Test for Suction Side Air Leaks

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Step 7

Threaded Fittings - Use any of the 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 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 any type of 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 you're 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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(81 to 120 of 181)

 Posted: 3/19/2018 

When I put the filter in circulate position the pump works and is pulling water but when I put into filter position I lose pressure and the pump won't pull water. I took filter apart and nothing is cracked and my filter is clean no broken grids and I put new DE. I don't know what could be the problem.

 Posted: 3/10/2018 

I have a pump that now won't prime. Sometime over the winter (the pool pump runs for 6 hours a day every other day) evidently it lost water flow and the plastic strainer basket on the pump housing melted and got sucked into the impeller. I took the pump apart and everything looks fine, put it back together and still won't prime. Any ideas?

 Posted: 2/17/2018 

Thank you so much for posting the DIY videos. I now know what an impeller is, how to clean it and how to prime the pump. All working again, thanks to you!

 Posted: 1/9/2018 

Mike P - It sounds like you may have reduced flow in one of your Spa lines caused by a partial blockage. Try snaking a line down each of the spa lines to loosen it up or try blowing it out with a King Drain hose adapter. I tried to think of what else could have happened when your pump failed that could have contributed to your problem but could not think of anything.

 Posted: 1/5/2018 

Stumped!!! 30,000 gallon pool with in ground spa, spa water level is 3 feet higher than pool water level (raised spa). Hayward super pump 1.5 hp. 2 1/2" pvc all around. Has worked fine for 12 years. One day, heard pump turn on and it was whining. I go check it and pump basket is not primed. Basket is warped from heat, etc. I figure, well, the pump just gave up the ghost, lost its prime after 12 years and failed. So, buy new hayward super pump. install myself. no problems. However, I went to use spa and in spa mode (pump drawing from spa and returning to spa), the pump basket would only be 1/2 filled. As soon as I switch to pool mode (pump drawing from pool and returning to pool), the pump basket would fill. PSI readings during pool mode 20psi, spa mode 33psi (small spa) PSI's unchanged from new. I've soaked and cleaned filters. I've even ran the cartridge housing without the filter cartridges and PSI is still 20/33 pool/spa mode AND pool mode works fine, spa mode still has pump basket with half water. The biggest problem is the heater for the spa will pop and act like its boiling the water off during spa mode. Pool mode it runs fine. At one point during my struggle, I put the pump in spa "empty" mode and it failed to empty the spa all the way. It drew the level down to about a foot of water and stopped. There is only one 3-way Jandy valve between the spa/pool and pump. It selects where the water draws from. My first suspicion was a leak at this valve. I have replaced the o-rings in this valve and the valve appears to not be leaking. I do have small leaks on the pressure side of things. One at the pump outlet (I didn't use enough teflon) and one at the other Jandy valve, which i just need to replace o-rings. but until i find this culprit and rule out replacing the whole works, I'm gonna wait on those. Help me not call a "professional" to come charge me $1,000 to diagnose this.

 Posted: 12/27/2017 

Zachary - If your pump was running dry, there is a good chance, as you indicate, that your shaft seal was damaged and would need to be replaced. And as long as you are replacing the shaft seal, I would buy a GOKIT and replace all the pump seals. Also, while you have the pump apart, you can check for a plugged impeller. It's a common problem.

 Posted: 12/19/2017 

This afternoon I found the water was not going into the skimmer. It turns out, the pump was not priming for who knows how many days. The motor sounded normal. When the motor was on it would suck all the water out of the basket area while very a slow stream of water came from the pool. Is the shaft seal the only possible culprit? Or could the impeller be clogged? Thanks for the help.

 Posted: 10/26/2017 

The bearings in our motor went out so we had to replace the motor. The pool was turned off for 9 days while we dealt with this. We replaced the motor today and turned it on. The motor is running but it doesn't sound like it's even trying to prime. There is no movement of water in the strainer basket. I checked all the valves and everything is open (I had it closed for the 9 days.) I tried filling the strainer basket - no change. I put the garden hose in the skimmer suction hole - no change, but now the pool is very full. Any suggestions?

InyoPools Product Specialist  Posted: 9/13/2017 

Akiko - When your pump runs dry for a period of time, it generates a lot of heat that can damage your shaft seal and pump gaskets. I would recommend buying the GOKIT for your pump and replacing all the gaskets/seals. See our guides on "How To Replace a Pool Motor Shaft Seal" and "How To Replace Pool Pump Gaskets" for more information.

 Posted: 9/5/2017 

This morning I found the water was not flowing into the skimmer. It turns out, the pump was not priming for who knows how many days. The motor sounded normal. I tried Step 2, and saw a leak under the motor. When the motor was on, the leak stopped, but sucked all the water out of the basket area while no water came from the pool. Is the shaft seal the only possible culprit? Thank you for your help.

InyoPools Product Specialist  Posted: 9/4/2017 

Sheree - It sounds like you may have a large suction leak on the suction side of your pump. As your pump builds up pressure, it could be sucking in enough air through this leak to lose prime. Check for leaks at the base of your skimmer, any of your suction side diverter valves, any suction side unions, the O-ring under your pump cover and the suction side drain plug at the base of your pump.

 Posted: 9/3/2017 

I have been having such a problem with my pool! It's green more than it has been blue! It will prime, but it will not keep its prime. Within 3 minutes (or less) it stops. We had someone come out and "fix" it.....$650 later and it is still doing the exact same thing. We replaced the suction line that leads into the basket, the propeller is clear and I am at a loss! Please help!!

InyoPools Product Specialist  Posted: 8/22/2017 

ceci - Check the O-rings of the old pump against the O-rings of the new pump to make sure the new pump has them all. Priming issues are in the front end of the pump, so check the strainer cover O-ring and the diffuser gasket first.

 Posted: 8/21/2017 

I replaced my pool pump because it makes noises with a CENTAURUS Swimming Pool Pump 2.7HP 2000W Electric Self Priming Spa Water Filter, both exactly the same brand and model, but the old one stills work and the new one doesn't suck water

 Posted: 7/23/2017 

I have a waterfall/pond which I'm having problems with. During the day it appears to run fine. I usually run it from 4pm to 10:30. In the morning the basket loses water and doesn't have enough to prime. I've replaced the pump and sealed the lid. Any suggestions or ideas what I could do to determine the problem.

 Posted: 4/16/2019 

Mine will prime up air starts building in my filter almost imedily

InyoPools Product Specialist  Posted: 4/17/2019 

Hello Sonny - It is normal for air to build up initially in the filter after the is primed and starts up. If you have an air relief valve, you can bleed the air from the filter. If your filter does not have an air relief, the air will eventually work itself out.

InyoPools Product Specialist  Posted: 7/10/2017 

Anonymous (priming) - When you turn your pump off, does water surge backwards from the pump to the skimmer? If so, you may have a suction air leak before the pump that allows air to build up in the top of the tank. This cause backpressure which pushes the water out of the pump and front pipes when the pump is turned off. See our guide on "How to Identify and Correct Air Leaks".

Anonymous  Posted: 7/8/2017 

My pump won't prime on startup so I fill the strainer basket and all works fine. Pool is full, no loss of water level, impeller is clear and seal on basket fine. What's causing the lose of the prime?



InyoPools Product Specialist  Posted: 7/3/2017 

Anonymous (priming pump) - When you try to fill the strainer basket, all you are trying to do is yet some water into the pipes before the pump. Some baskets, depending on their relative height to the pool, will not fill or will not retain the water. Fill the pipes and close the cover quickly, then turn the pump on. There should be enough water in the pipes to prime the pump.

Anonymous  Posted: 7/1/2017 

I have tried to fill up the pump basket as suggested in step 2, but the basket will not fill up. Even with me leaving the water hose running for awhile. Which means in order for me to turn the pump back on, there will be no water in the basket. What could be the causing the pump basket not to fill up?

Thank you,
Desperate Texan


InyoPools Product Specialist  Posted: 7/1/2017 

Diane - Hopefully your problems are not underground. I would first check the gaskets and connections at the pump and between the pump and the skimmer. Check the O-ring on the pump's strainer cover first. See our guide on "How to Identify and Correct Air Leaks" for more information.

InyoPools Product Specialist  Posted: 6/30/2017 

Maggie - It sounds like you have a suction leak that is causing backpressure in the top of the tank. I would still look at replacing the pump basket gasket. When you are in recirculate mode, the filter is bypassed. Any air coming into the system is routed right back to the pool so that air cannot build up in the filter.

 Posted: 6/30/2017 

Awe have tried to prime basket with Jose water however water still not coming thru could leak be in line that runs from skimmer box to pump which is under ground thank uou

 Posted: 6/28/2017 

I have a 30,000 gallon pool with a super Hayward pump. The pump seems to pull vacuum fine in the recirculate mode but once you move the indicator filter it seems to loose water in the filter basket after an hour or so. Changed O rings on the filter, have suction in the pool both summers and main, and have tightened all union connections. Any suggestions on what could be causing this. I thought pump basket gasket but it doesn't loose anything in the recirculate mode as stated.

InyoPools Product Specialist  Posted: 6/19/2017 

Michele - No, a cut gasket would leak and when they are stretch like that, they tend to overlap on themselves and also leak. Your stretched gasket should be replaced with a new one.

 Posted: 6/17/2017 

I took the seal off our skimmer on the pump and brought it to pool supply. They looked at it and said it was fine. When I put it back 2gthr the square ring was stretched out. Can I cut it to make it fit?

InyoPools Product Specialist  Posted: 5/30/2017 

crazy4brady - I would have recommended a 1 1/2 HP single speed or varialbe speed pump for your size pool. If you can afford the initial purchase, a VS pump can save you up to 80% of your operational costs. A couple other things to check. Make sure the pump's impeller is not clogged. See our guide on "How To Clean Out a Pool Pump Impellers ". And when you purchased this pump, did you buy the right one. If you have an in-ground pool, you need an in-ground pump. Above ground pool uses an above ground pump. An AG pump is installed at the base of the AG pool because it need gravity to prime the pump.

 Posted: 5/28/2017 

We purchased a Doheny pool pump 1hp for our 20x40 pool. We have always used 1 1/2 hp in the past but were told 1hp would be enough for our pool size. We have trouble keeping this pump primed. We replaced the skimmer and skimmer line last spring, so we know that it's not that. What could be causing the problem?

InyoPools Product Specialist  Posted: 5/14/2017 

Anthony - If your housing gasket has a leak, you would see water squirting out at the break when the pump is operating. Did you replace the other motor pump gaskets when you replaced the motor? As a minimum, you should have replaced the shaft seal. All the pump gaskets are sold in a package called a GoKit. The GoKit for your Sta-Rite Max-E-Pro pump is GOKIT79.

 Posted: 5/11/2017 

I purchased a pump motor to replace a worn one from Inyopools, replaced the gasket on the pump housing (Sta-Rite Max-e-Pro) and it works fine until the pump is shut off. Then all the water drains out of the basket and it loses prime.

It seems like the new gasket is the problem, how can this be?


InyoPools Product Specialist  Posted: 4/26/2017 

Pmw - I'm not sure what you are referring to as "the little bottle on the pump". If you are referring to the little (1 1/2") bottle on the side of your filter's multiport valve, you don't have a problem. This bottle only fills up when you are backwashing the filter. It tells you when the waste water changes from dirty water to clear.

 Posted: 4/25/2017 

I finally got my pump primed. Still unsure of what the problem was as never occurred before. Now the little bottle of water on the pump won't fill up with water. What can I do and should I not run pump until it is full?

InyoPools Product Specialist  Posted: 4/17/2017 

Tomasz - I'm not sure I understand your question. Is the switch at the "T" a diverter valve that allows you to shut off the main drain but you have no way of inserting a hose at or around the pump going to that "T"? If so, you might consider putting unions on the input and output ports of your pump that would allow you to remove the pump and give you access for the hose.

 Posted: 4/16/2017 

You said: "Try blowing the clog out with a drain cleaner bladder. It’s most effective if you insert it at the pump going back to the pool." How do I do that? The pipe from the pump has a tee with the switch between the skimmer and main drain. I have no access to the pipe after that ...

InyoPools Product Specialist  Posted: 3/31/2017 

anonymous (cover O-ring) - No, I would not glue the strainer cover O-ring down. I would suggest lubricating the top of the O-ring when each time you replace the cover.

Anonymous  Posted: 3/30/2017 

I replaced the strainer basket o-ring because I was having issues with air getting in. There was a residue left underneath; it looked like the previous o-ring had been glued down but the o-ring came up easily and all intact?. I had to scrape out the residue with a screwdriver, which was not easy to remove but you could tell it was somewhat flexible. When I lift the lid now the o-ring comes out every time, but it did not use to, which is frustrating. Should I "glue" my o-ring down? If so, what do you use? Thank you!

InyoPools Product Specialist  Posted: 3/28/2017 

Este - Generally, when you add water to the basket, some of it does flow back into the pool. You are just trying to get some water into the system to partially fill the input pipes. If your system won't prime with partially filled pipes, you might replace the strainer basket O-ring. It may not be sealing properly.

 Posted: 3/27/2017 

When ever my pump needed priming, I used to add water to the pump basket for about 3 mins then water will fill the pipe going to the pool and fill the basket. I will close lid and start the filter and everything would be fine. The issue now is I cant fill the basket any more. Water just flows into pool and doesn't fill the pipe and basket. Any ideas? Thank you.

InyoPools Product Specialist  Posted: 3/23/2017 

Tony - If you shut the pump off right away, you should be ok. Try running water into the pump's strainer basket to fill up some of the lines before you turn the pump on. Before you reattach the cleaner, hold its hose under water to eliminate the air in the hose.