How To Replace a Pool Pump Capacitor


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Save yourself the cost of a new motor. Check the capacitor first. When you turn on your pump and the motor produces a humming sound, the motor may be frozen so that it won't turn or you may have a bad capacitor. Check the capacitor. It can be replaced for a fraction of the price of a new motor. Note: Some motors have two capacitors: a run capacitor and a start capacitor. If so, check both.

Click Here to View Pump Motor Parts (Including Run & Start Capacitors, Bearings, and Switches) 


Step by Step


Step 1

Turn off the power to the pool pump. For maximum safety turn the power off at the circuit breaker.

Step 2

Depending on the make of the pool pump, the capacitor will be under a hump cover on top of the motor, or it will be under a cover on the electrical end of the motor, or both. Some pumps have both a run capacitor and a start capacitor. The run capacitor will generally be rated at 15-50 MFD and 370 VAC. The start capacitor will generatlly be rated at 50-400 MFD and 125 or 250 VAC. This picture shows the location of the capacitor under a hump cover.

Click Here to View Pump Motor Parts (Including Run & Start Capacitors, Bearings, and Switches) 

Step 3

This picture shows the location of the pool pump capacitor at the end. In either case the covers are normally held on with two screws. Remove these screws to take off the cover and expose the capacitor. This capacitor is about the size of a roll of half dollars.

Step 4

Pool Pump Capacitors store an electrical charge that can shock you even when the power is off. Before removing the capacitor, discharge this energy by placing a screwdriver across the leads of the capacitor. CAUTION: Capacitors have been know to explode when shorted out. For your protection wear eye protection and place a cloth over the capacitor before shorting it out.

Step 5

If the capacitor is located at the end of the pool pump, remove the single screw that secures a clip holding the capacitor. Note how the plastic strip is positioned between the clip and the capacitor. It will have to be replaced in this position to keep the capacitor from shorting out on the motor. If the pool pump capacitor is on top of the motor, it should be free after you have removed the cover and the capacitor's leads.

Click Here to View Pump Motor Parts (Including Run & Start Capacitors, Bearings, and Switches) 

Step 6

Remove the leads to the pool pump capacitor. Note the placement of the leads so that you can restore them to their correct position when you reconnect them.

Step 7

Check the rating on the pool pump capacitor for replacement specifications. They will vary by manufacturer. Look for their MFD (or uf) and VAC specifications. For example, this one is a start capacitor rated at 124-149 MFD and 125 VAC. Try to replace the bad capacitor with an identical capacitor. If the exact capacitor is not available, you can use one with slightly higher capacitance. Do not use one with a lower rating.

Click Here to View Pump Motor Parts (Including Run & Start Capacitors, Bearings, and Switches) 

Step 8

Use a multimeter to verify that the capacitor is bad. Using the lowest ohms setting, touch the meter leads to the pool pump capacitor's terminals. If meter remains at 0, you know that the capacitor is bad. Check the new capacitor to verify it is good. First short out the terminals on the new capacitor to reset it. Then touch the meter leads to the capacitor terminals. If the capacitor is good, the meter will jump up to the other end than slower back off to 0.

Step 9

Connect the motor leads to the pool pump capacitor and secure the capacitor in place as required. Watch the placement of the plastic strip as mentioned above.

Step 10

Replace the cover.

Step 11

Reestablish power at the circuit breaker.


(81 to 120 of 212)

 Posted: 4/20/2017 

Replacing a destroyed start capacitor 161-193 on a Sta Rite pump motor C48L2PA105. Need assistance in hooking up the three leads (2 yellow and 1 red/white). your photos indicate yellow leads attach to same set of terminals and red/white to other set. Does it matter which set of termnials they are hooked to? Thanks


InyoPools Product Specialist  Posted: 3/27/2017 

NHCannon16 - Try placing the foam on top of the capacitor. Also make sure that your replacement capacitor at least matches the old capacitor. In this case, it sounds like 370V 30uf. If you pump motor is continually burning up capacitors, try using the next one up in size. Capacitors are susceptible to power variations or increases. If you can't control your system power, you may need a capacitor with a little higher rating - 370V 35uf.

 Posted: 3/26/2017 

I just replaced the capacitor on my Pentair Challenger II and the pump ran for less than 30 seconds and then shut down. Smelled a burning smell and I turned off and flipped the switch on the fuse box. I replaced a 30uf with a 30uf. The capacitor is on top of the motor in the "hump" and when I replaced it, the foam cover was not sitting on top of the capacitor, but placed beneath it. In pictures online of other motors that foam piece is above the capacitor. Could it have shorted out on the metal cover? Any ideas as to what to do next?

 Posted: 3/6/2017 

Thank you very much for your help! Order incoming shortly.

InyoPools Product Specialist  Posted: 3/6/2017 

Richard - How do you switch between the two speeds? I would check the hi/low switch or the wiring from the switch to the motor.

InyoPools Product Specialist  Posted: 3/6/2017 

James Blilie - We show that the C48K2P10S is a two-speed 1 HP motor. It has a manufacturer equivalent part # of UQS1102R. This motor has two capacitors: the start capacitor is 610807-001 (5270-11); the run capacitor is 628318-309 (5270-02).

 Posted: 3/4/2017 

Jus replaced hot tub motor, two speed. First speed comes on in plugged in, but second speed won't. Can hear relay switching in panel. Unplugged new pump and plugged in old pump, both speeds work fine. Could this be a capacitor? Again a brand new motor. Not hearing any humming when I try, jus first speed running constantly. Thanks for any help.

 Posted: 3/3/2017 

Thanks! I have that motor model number: C48K2P105.

It's about 0-deg F out here right now, so I'm trying to avoid outdoor work ...



InyoPools Product Specialist  Posted: 3/2/2017 

James Blilie - Look for the MFD (or uf) and VAC specifications on the start capacitor. For example, 124-149 MFD and 125 VAC. If you can't read this, we would need the motor model # on the metal plate of the motor. Your pump can be configured with different motors.

InyoPools Product Specialist  Posted: 3/2/2017 

smoking capacitor - If the capacitor is smoking, it should be replaced. If you can give us the motor model that's on the metal label of the motor, we would be able to give you the capacitor id. Or better yet, see if you can read the capacitor specs on the start capacitor for example 124-149 MFD and 125 VAC.

 Posted: 3/2/2017 

Hello, I need to replace my start capacitor. I have a Sta-Rite Dura-Glas pump, model P2RA5YE-181L. Can you please tell me the correct start capacitor part number? Thanks you!

Anonymous  Posted: 3/1/2017 

have an older Franklin 778 pool pump. After turning on the capacitator will start to smoke after a few minutes. Disassembled the pump and everything moves freely. Does this sound like a capacitator problem?

InyoPools Product Specialist  Posted: 12/12/2016 

Pumpprob - Generally, a whining motor does indicate your motor bearings are starting to fail especially if you have an older pump.

 Posted: 12/7/2016 

I have a pentagram pool pump system...the motor is making a whining noise and is hot to the this bearings?

InyoPools Product Specialist  Posted: 12/5/2016 

Raymond - Your K48M2P105B1 motor has two capacitors: the run capacitor is on the top under the bump. The start capacitor is under the cover in the back of the motor. The start capacitor is part number 2509516-002, 64/77 MFD, 250 volts. The run capacitor is 2522881-001, 35 MFD, 440 volts.

 Posted: 12/3/2016 

I have a Sta-Rite (AO Smith) motor K48M2P105B1 2HP hot tub motor;
the run capacitor is 35 microF 370VAC but the numbers smugded off the start capacitor when I touched it. Can't find a lookup table for the motor and hoping you know. Thanks


InyoPools Product Specialist  Posted: 10/12/2016 

ComFuzed - From your description, I would say that a bad start capacitor is likely. I'd replace it. It's relatively easy and inexpensive.

 Posted: 10/11/2016 

Not sure at all if this is just a capacitor problem (close though)
Sta-Rite pump and motor (AO SMITH). Back-end of motor is a dead ringer for the Hayward in the pics above.
Capacitor 161-193 mF 110 VAC
(Not an AC person, lots of experience with DC)
1. Motor will not start, but growls (not what I'd call a "hum", but maybe lack of experience)
2. Cracked the pump and checked the impeller cavity (empty) and it spins freely using two fingers (so I have not disassembled the wet end) nor do I see or suspect a leak of any kind.
3. Resistance check on the capacitor jumps to 10-15K then slowly to infinity (not a jump to zero as some sources say, but my meter only goes up to 1K range).
4. Wiring conduit is aged and was actually cracked open in spots when I inspected it, but I saw no sign of corrosion/water damage on the connector or the wires.
5. Failure only started after an extended (clear weather) power outage (3 hrs). Don't really know if there was a spike before it went out since just about everything else in the house has protection (Florida ... lightening ... need I say more?)

So, original question, is this likely the capacitor?

Oh, one other thing. The plastic guard on the cap. was browned (heat damage?) and the outer casing of the cap. looks "rough" near the end away from the contacts (matches position of browning on guard) Would the cap. have acted as surge stop?

Thanks for any advice you can give me!


 Posted: 9/15/2016 

Power company changed out meter yesterday - took several seconds for everything to come back up. Pool pump hummed when I turned it on this morning - used your website to troubleshoot. Local pool supply had the correct part in stock - about a minute to change out the part and pump started and runs fine. Many thanks!

InyoPools Product Specialist  Posted: 8/15/2016 

PerplexEd - Sounds like a bad start capacitor. Try replacing the capacitor. If that doesn't work, you may have a dead spot in your motor windings and you would generally have to replace the motor.

 Posted: 8/13/2016 

Pump run fine, makes a hard humming sound when trying to start,then kicks the breaker out. It will start after several attempts.

InyoPools Product Specialist  Posted: 7/25/2016 

Sean - Many above ground pump motors do not have a start capacitor. It is likely that your Tidal Wave pump does not.

 Posted: 7/24/2016 

Thank you very much for the information. Can you let me know where the capacitor for a dual port Tidal Wave pump is located? My manual did not have it listed and could not find it anywhere on line. It is not located at the back the same as what this video demonstrates. Appreciate any help.

InyoPools Product Specialist  Posted: 7/6/2016 

wharton94 - According to the motor rep: "The capacitor should be the higher voltage if it is to last, but would not make a difference starting the motor. A shorted winding, or a start switch may also be the problem". See our guide on "How To Replace AO Smith Motor Parts - Overview" for more information.

InyoPools Product Specialist  Posted: 7/5/2016 

wharton94 - Humming is generally resolved by replacing the start capacitor like you did. I sent an email to our motor reps to see what capacitor they would recommend and if the windings could have shorted. Will get back to you.

 Posted: 7/2/2016 

One day the high speed pump on my hot tub would only hum when I tried to turn it on. (It uses a 240v Emerson T55CXBNC-999 motor) After troubleshooting, I learned:
1.The motor shaft would turn freely (motor/pump were not frozen or jammed).
2. Spinning the motor shaft with a screwdriver (through the access hole) and concurrently turning on electricity to the pump, would fire up the motor and it would run just fine as long as needed.
3. Once the running motor/pump were turned off and subsequently turned back on again, the unit reverted back to simply humming only.

I pulled the motor and checked both the run and start capacitors - and found the latter was bad (which made sense). The original Aerovox start capacitor was rated 130-154 MFD @ 165VAC. I replaced it with your part #5270-12 which is rated 130-156 MFD @ 125VAC and reassembled the motor. But upon change...still just hums!
Now I'm wondering two questions:
1. Did I buy the wrong capacitor? The odd 165VAC rating of the original capacitor threw me a curve (especially since it is a 240 volt motor).
2. If the capacitor is probably not the issue, can a burned out winding allow the motor to run normally (once started), but not allow it to start on its own?

BTW, I want to throw you folks a huge kudo for maintaining this Q&A area on your website. It is a great source of information for DIY'ers like myself - and it's greatly appreciated!


InyoPools Product Specialist  Posted: 6/26/2016 

gunnyt - Very sorry for the delay. This is our busiest time of the year and unfortunately, sometimes our calls and chats get backed up. We generally have a very good response rate.

 Posted: 6/24/2016 

hey guys what gives? im on live chat and i'm told have to check on capacitor will take a few min. 20 min later i get We're not around, but we'd love to chat another time

InyoPools Product Specialist  Posted: 6/21/2016 

Vana - If you are replacing your current capacitor with one of a smaller diameter, it sounds like you are using a smaller rated capacitor. See Step 7. You cannot replace a capacitor with one of a lower rating.

 Posted: 6/20/2016 

How can you "buffer" the holding clip if the new capacitor is a smaller diameter than the old one? I tried bending the clip some but it wasn't enough. Thanks in advance.

 Posted: 6/19/2016 

I wanted to say thank you for providing this resource! I have learned a little!

InyoPools Product Specialist  Posted: 5/3/2016 

wade - Sounds like you have a serious motor problem like shorted out windings. If you have had the pump for a while, it may be time to buy another one.

 Posted: 5/1/2016 

my husband replaced the capacitor on our 2 hp inground pool pump and it blew up 2 separate ones . Old one pump didn't work at allis why replaced it

InyoPools Product Specialist  Posted: 4/15/2016 

Vern 0- See our guides on "How To Troubleshoot a Pool Pump Motor - Motor Overheated" and "How To Troubleshoot a Pool Pump Motor - Motor Shuts Down".

 Posted: 4/14/2016 

My pool Jandy flopro .75hp pump is overheating and stops running after about 45 seconds then restarts after another couple of minutes. Is this because of a bad capacitor? If not what would you recommend.

InyoPools Product Specialist  Posted: 4/5/2016 

TB DFW - The motor for your 2HP Pentair Superflo Pump is a B2748 and the run capacitor for that motor is specified for 30 MFD / 370V - our part number - 5270-05. You should be able to verify this by comparing it to the specs printed on the old capacitor.

 Posted: 4/3/2016 

I am having trouble finding the right size run capacitor for my 2HP pentair Superflo pump. Model number is ST-N1-2A/ 340040. Does anyone have a resource for this info.

InyoPools Product Specialist  Posted: 3/11/2016 

foreclosure - I would try replacing the capacitor first. It's a quick and inexpensive fix. You might also consider changing the sand in your filter. When you start to clean out the green pool, remove the heavier debris out of the pool with a pool net or rake before running the pump so you don't clog the filter. Than go through the process in our guide on "How to Treat Moderate Swimming Pool Algae" to clear your pool.

Anonymous  Posted: 3/9/2016 

I just bought a forclosure with an in ground pool. Would it be best to just replace the pump and filter since I don't know what I have? The motor only hums and the water is very green. It has a sand filter.

InyoPools Product Specialist  Posted: 11/6/2015 

Endlesspool - I know of no way to cut a pump's rpm by reducing the electrical current flow. You might ask a motor repair shop, but I think you are looking at a major design change.