How To Determine Why a Pool Pump Won't Prime

WRITTEN BY:  Inyo Pools

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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.


Step by Step


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.


(1 to 40 of 97)

Cindy  Posted: 02/17/2018 15:35 PM 

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!

Inyopools  Posted: 01/09/2018 12:05 PM  Inyo Product Specialist

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.

Mike P.  Posted: 01/05/2018 0:25 AM 

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.

Inyopools  Posted: 12/27/2017 14:25 PM  Inyo Product Specialist

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.

Zachary  Posted: 12/19/2017 14:20 PM 

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.

Missy  Posted: 10/26/2017 22:43 PM 

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  Posted: 09/13/2017 15:13 PM  Inyo Product Specialist

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.

Akiko  Posted: 09/05/2017 16:21 PM 

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  Posted: 09/04/2017 12:08 PM  Inyo Product Specialist

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.

Sheree  Posted: 09/03/2017 10:35 AM 

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  Posted: 08/22/2017 13:45 PM  Inyo Product Specialist

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.

ceci  Posted: 08/21/2017 22:58 PM 

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

Waterfall problem  Posted: 07/23/2017 10:01 AM 

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.

Inyopools  Posted: 07/10/2017 10:45 AM  Inyo Product Specialist

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: 07/08/2017 11:00 AM 

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  Posted: 07/03/2017 11:26 AM  Inyo Product Specialist

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: 07/01/2017 18:21 PM 

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  Posted: 07/01/2017 13:01 PM  Inyo Product Specialist

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  Posted: 06/30/2017 10:33 AM  Inyo Product Specialist

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.

Diane  Posted: 06/30/2017 9:46 AM 

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

Maggie  Posted: 06/28/2017 2:07 AM 

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  Posted: 06/19/2017 14:25 PM  Inyo Product Specialist

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.

michele  Posted: 06/17/2017 19:14 PM 

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  Posted: 05/30/2017 10:36 AM  Inyo Product Specialist

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.

crazy4brady  Posted: 05/28/2017 15:08 PM 

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  Posted: 05/14/2017 16:38 PM  Inyo Product Specialist

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.

Anthony  Posted: 05/11/2017 9:38 AM 

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  Posted: 04/26/2017 10:22 AM  Inyo Product Specialist

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.

Pmw  Posted: 04/25/2017 18:26 PM 

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  Posted: 04/17/2017 12:22 PM  Inyo Product Specialist

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.

Tomasz  Posted: 04/16/2017 18:26 PM 

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  Posted: 03/31/2017 12:57 PM  Inyo Product Specialist

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: 03/30/2017 6:11 AM 

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  Posted: 03/28/2017 12:58 PM  Inyo Product Specialist

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.

Este  Posted: 03/27/2017 9:35 AM 

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  Posted: 03/23/2017 16:29 PM  Inyo Product Specialist

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.

Tony  Posted: 03/21/2017 23:06 PM 

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?

Inyopools  Posted: 03/20/2017 11:54 AM  Inyo Product Specialist

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.

Inyopools  Posted: 03/20/2017 10:13 AM  Inyo Product Specialist

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.

paul  Posted: 03/19/2017 13:58 PM 

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.