How To Determine Why a Motor Won't Start or Shuts Off

WRITTEN BY:  Inyo Pools

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This guide discusses the common problems related to a motor that won't start or once it does start shuts off after 5 minutes.

Step by Step


Step 1

No power to the motor- Check for improper or loose connections, open switches or relays and blown circuit breakers or fuses. Check for broken power cords.

Step 2

Jammed motor - Check that the motor shaft rotates easily. If it's stuck, check that the impeller is not jammed with debris. Check that the impeller or diffuser is not broken. If the impeller is good, you problem may be bad motor bearings. Replace bearings/motor or impeller as required.

Step 3

Motor hums but will not turn over - Check for a bad capacitor. You may have two: a run capacitor and a start capacitor. Some motor have a governor at the electrical end of the shaft. Check that it is not stuck open. If your capacitor(s) and governor are good and the motor shaft rotates easily you probably have a burned out motor coil and you will need to repair or replace the motor.

Step 4

Motor gets hot and shuts down - Generally due to low voltage or being overloaded. Check that the motor is wired correctly. If the motor is configured for 230V and has 115V coming in, it will shut down after running 3-5 minutes. Check for loose connections. Check for undersized wiring. For a hook-up to the circuit box of under 50', pumps of up to 2HP wired for 230V need No. 14 size wire, For pumps wired for 115V, the wire size must be No. 14 for 1/2 and 3/4 HP; No 12 for 1 HP; and No. 10 for 1 1/2 and 2 HP. Check that the motor is not overloaded. Does the pump have the correct impeller and diffuser for this motor? Is the impeller worn and rubbing on the diffuser.

Step 5

Note: Most pump motors have Automatic Thermal Overload Protection. The motor will automatically shut off before the motor generates enough heat to damage itself. Once a normal heat level is reached, the motor will automatically restart. CAUTION: If the motor operates in this on/off mode for any length of time it will burn out.


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Chris  Posted: 11/09/2017 20:39 PM 

I came home last week to a no flow light on my panel. Checked the pump and it hummed, but didn't start - and was getting 230V across L1/L2. Odd thing was that the heater started to fire up while the pump was humming, even though the heater was set to off. As the pump was 12 years old and a little noisy, I decided to order a replacement Century SN1202 from Inyo (and a new impeller and gasket kit). I installed all the new stuff today and had the exact same problem when I was done...pump hums and the heater kicks on. As before, I'm getting 230V across L1/L2. Any ideas before I call the pool dude? thx

CarlB.  Posted: 10/31/2017 18:46 PM 

Hello. When I turn on my booster pump while the filter pump is running the filter pump shuts off. This causes no flow to go to my heater so I get this boiling sound in side the heater. The system was installed in May. It is a Jandy variable speed pump and 1.5 horsepower booster pump. This problem just started maybe a month ago. Thanks.

DAvid  Posted: 09/13/2017 23:19 PM 


funny thing. Exact same thing happened to me. I also did the exact same test as you measure the voltage from ground to L1 and ground to L2, both were reading 110V AC. I did NOT however, check it with another power cord. Have you figured out what's wrong?


Inyopools  Posted: 07/21/2017 13:43 PM  Inyo Product Specialist

Maxair - I would bet that the low side of the switch has failed. Try replacing the switch.

Maxair  Posted: 07/19/2017 7:42 AM 

hi-flo ph2200-6 1 yr old only turns on HI. the Low setting wont work.

Inyopools  Posted: 07/09/2017 17:04 PM  Inyo Product Specialist

Kevin - I would have been surprised if both of your motors failed at the same time, so I would have questioned the circuitry to the motors? If you said you measured 120V on both the L1 and the L2 leads against a ground, you should have 230V across L1 and L2 which means your supply voltage is 220V. Are your motors configured for 220V? When you said you plugged an extension cord into an outlet, was that an 115V outlet. Are your old motors set up for 115V?

Kevin  Posted: 07/07/2017 11:46 AM 

Hello, my two pool motors (1HP and 0.75 HP) have suddenly both stopped working (no humming, completely dead). Naturally I assumed the motors were broken as they looked very old. So I bought two replacement motors from here, hooked both up the same way the old ones were and still absolutely dead. I checked the Voltage on both motors (GND to L1, and GND to L2) both read 120V. So what on earth can be the problem? Side note (don't try this, danger): To make sure that the issue isn't the motors, I took an old extension cord and cut it to expose the 3 wires, plugged it into an outlet and held the wires to the OLD motor, and surprise it started running. Thus the old motors were probably not broken and something must be wrong elsewhere. ANY IDEAS??

Inyopools  Posted: 07/01/2017 12:36 PM  Inyo Product Specialist

Bnd31 - The motor humming is a symptom of a bad start capacitor. So I would replace that first. Usually, the start capacitor is in the back of the motor and the run capacitor is on the top. I'm not sure why the motor stops after a few minutes. It sounds like your thermal overload protector is cutting the motor off because the motor is too hot or the thermal overload protector has gone bad. Otherwise, your motor may be going bad. Try replacing the run capacitor if your motor has one. See our guide on “How To Replace AO Smith Motor Parts – Overview” for motor parts information.

Inyopools  Posted: 06/30/2017 12:35 PM  Inyo Product Specialist

Anonymous (pump won't start) - I see no correlation between backwashing the excess water from your pool, and your pump subsequently not turning on. If it's humming, it may need a new start capacitor. Note: if your MPV has a Waste option, you should use that setting instead of Backwash to drain off your pool but that should have no impact on your motor not starting.

Bnd31  Posted: 06/30/2017 1:51 AM 

When I turn the pump on, It just hums but dont start. Im able to start it by turning the shaft and turning the pump on at the same time. But it shuts off by itself in few mins. Then it wont hum at all if i try to start right away. If i let it sit for a while, i hear the click, then i turn the pump on, hums, turn the shaft and starts.. dies again in a while..

Any help?? I havent checked the capacitor yet, looks like theres one at the top of the pump. And abt the wiring issues, low and hight voltage issues, i have never altered anything at all. We moved in last year and the pump has been working fine so far

Anonymous  Posted: 06/29/2017 2:30 AM 

I stupidly forgot to turn the garden hose off, filling my pool with water for 9-10hrs, I backwashed all the excess water and it's back at its regular level, however, the pump won't turn on.
What do I do? It was working fine earlier

Inyopools  Posted: 06/14/2017 10:17 AM  Inyo Product Specialist

Anonymous (dead motor) - Make sure that your motor is configured to match your supply voltage. If you have 220V coming into the motor, the motor should be set up to receive 220V. Recheck your wiring. If the motor still doesn't work, talk to the dealer again. Have him check the motor.

Anonymous  Posted: 06/13/2017 17:29 PM 

Hello. I just replaced the motor on my pool pump. The old one was only two weeks old. The old one just stopped working. Took and exchanged the motor for another one. Hooked it back up, and nothing. Replaced breaker and timer. Still nothing. I know power is making it to the timer and motor. The motor is a century USQ1152. Not sure where to go from here. Thanks for any help. Bobby

Inyopools  Posted: 06/12/2017 17:45 PM  Inyo Product Specialist

Gary - You may be in an area with unstable supply voltage. Some motor reps have suggested switching to a run capacitor with the next level voltage. If you have 370V now, go up one level in voltage to 440V.

Inyopools  Posted: 06/11/2017 20:58 PM  Inyo Product Specialist

Ozzie - If you have a multimeter, check the voltage at the motor terminals L1 and L2 to see if your motor is getting power. If your motor has one or two capacitors, change them. Otherwise, your motor winding may have shorted out and you may need a new motor.

Gary  Posted: 06/11/2017 4:02 AM 

Hi there. Recently had to replace the run capacitor, Have used the same specs as the old one. New problem though, Motor starts fine but only runs for about 4 minutes and then stops for about 5 minutes, the whole process repeats. The control panel has 3 lights flashing when it stops and clears when motor starts up again. This problem is doiong my head in. Please Help.

Ozzie  Posted: 06/09/2017 16:07 PM 

Hi, I'm hoping someone can help. My pool pump is not turning on or making any noise. The intermatic timer is working as it is receiving power and I can see the gears moving through the visual motor check window. When I turn the intermatic timer on manual nothing happens. No humming noise or anything else, just nothing. What could this be? It was just working fine a couple of days ago. Thanks.

Inyopools  Posted: 06/08/2017 22:21 PM  Inyo Product Specialist

Vacekt - Check to make sure there isn't another capacitor under the back cap. If none, and you've replaced the top capacitor, you may have a short in the motor windings. Have a pool store verify this. You may need a new motor.

Vacekt  Posted: 06/06/2017 8:55 AM 

Century Centurion motor was humming but woudnt run. I checked for debris in impeller but it was clear. I tried it multiple time but just hummed. THEN IT STOPPED noise at all. I went ahead and changed the run capacitor. Didn't fix problem. Still doesn't run or even him.

Inyopools  Posted: 06/04/2017 21:51 PM  Inyo Product Specialist

Tubbs - Sorry, I don't understand your electrical circuit. Where is the pigtail connecting to?

Tubbs  Posted: 06/03/2017 18:32 PM 

When replacing my motor I have power going to the motor but as soon. As I plug the pigtail in I lose complete power to the motor.

R_W  Posted: 05/26/2017 12:26 PM 

My USQ1152 was running fine. I shut off the breaker to replace the ignitor/flame sensor on my heater and when I turned the breaker back on the pump wont run. I have power to the timer and out to the motor. Any suggestions?

Inyopools  Posted: 05/22/2017 11:27 AM  Inyo Product Specialist

rick - I assume with a new motor that the shaft turns freely before it was joined to the pump housing. It may be that the shaft seal wasn't seated correctly and is binding on the shaft. If you take the motor out of the housing, does the impeller spin freely, If not, reinstall the shaft seal. Make sure you have the right shaft seal - GOKIT32. Is the impeller too big for the pump? See if there are any wear marks inside the pump housing.

rick  Posted: 05/19/2017 12:12 PM 

first i replaced capacitor,didn't work.then i took motor to reapir shop,they suggested i buy a new one-repalced Pentair w-24 with new one ,does the same thing and the shaft will not turn?

Inyopools  Posted: 05/02/2017 11:55 AM  Inyo Product Specialist

chad - The windings on you motor may have shorted out. I would contact the place you bought the motor and see if the motor can be replaced. It should still be under warranty.

chad  Posted: 04/30/2017 11:10 AM 

Pool motor sometimes starts on a timer. But if have to power motor off for maintenance for a few minutes (to clean filter, etc), it buzzes and will not restart. I changed the capacitor with new. Same thing. The motor will hum then a click sounds. After 5-7 minutes the motor clicks again and tries to restart. If the motor does not start up after about 5 seconds the breaker trips. I also replace my breaker with new. The motor is only 6 months old and worked fine for 5 months.Where do I go from here?

Inyopools  Posted: 03/03/2017 10:07 AM  Inyo Product Specialist

pump won't start - try shutting the motor off at with a switch between the breaker and the pump, reset the breaker and turn the pump on at the switch. Check that the breaker is good.

Anonymous  Posted: 03/02/2017 16:46 PM 

pump was running, I opened breaker while pp was running, closed brk pump will not start. seems to be getting pwr to pump as per meter buzzing when conduit was checked. no humming at mtr

Inyopools  Posted: 01/09/2017 11:58 AM  Inyo Product Specialist

Anonymous (motor buzzing) - Buzzing is frequently a sign of a capacitor failing. I would replace the capacitor. If that doesn't work, your motor may have shorts in its windings and you may have to replace the motor.

Inyopools  Posted: 01/09/2017 11:51 AM  Inyo Product Specialist

Miami Grimgo - Sounds like the switch in the timer may be failing. Try bypassing the whole timer mechanism by wiring the timer input leads (1 and 3) to the timer output leads (2 and 4) so power is going directly to the pump from the breaker. If that powers up your pump and it stays powered, your should replace the timer mechanism.

Miami Grimgo  Posted: 01/07/2017 21:55 PM 

Here is my issue. I have an 2008 Hayward Super Pool pump set up with an intermatic timer. To this point it has worked fine. Like clockwork. However the other day I noticed the issue. The pump no longer turns on automatically. Moreover, even if I manually turn the switch on it does not start. When I turn the switch I see flashes as if there is electrical current, a clicking noise at the switch and 1/2 second sound of the pump trying to start. If I keep trying to manually turn on the pump eventually after say 5 - 10 trys.. will come on, prime and all is good. Then say anywhere from 15mins to an hour, the pump will shut off.

I replaced the capacitor as I thought this may be the issue. Same problems. I then replaced the motor with brand new motor. Same issue. It appears to be electrical and has to do with intermatic switch or breakers.

Anyone have an idea how to fix this?



Anonymous  Posted: 01/07/2017 16:11 PM 

Pool motor starts each morning (on a timer) fine. But if have to power motor off for maintenance for a few minutes (to clean filter, etc), it buzzes and will not restart. Have to leave it off for several hours (too cool down) before it will run again. Is this a capacitor or motor issue?

GeorgeC  Posted: 12/26/2016 23:18 PM 

If I understand the rep, it appears he is saying that there is a separate set of PSC windings for each speed. This would explain the symptoms. This motor (previous post) had the low speed cap burn out, so may have damaged the aux (start) winding. I'll check it out now that I think I understand the wiring better. In the end I may need a new motor, but may be able to nurse it through the cold days of winter.
What made this so difficult to understand was that all the PSC circuits shown online use one cap, and if multispeed use taps at different points on the main winding (either changing the poles or just adding resistance). It was assumed that the speed control relay on top was controlling these taps-- it now appears it switches between the two separate sets of windings in the single case. This appears to be a common spa motor setup (the one next to it, by a different manufacturer, looks exactly the same); why there is nothing specifically about them online is hard to explain.
I appreciate you taking the time to look into this puzzle, and over the holidays too! May be back in the Spring for a motor if it's not an easy fix.
Happy New Year,

Inyopools  Posted: 12/21/2016 10:54 AM  Inyo Product Specialist

GeorgeC - We asked the Century motor rep for his insight and here's his response. "This is likely a PSC motor on both high and low speeds. If the low speed has either a bad main or phase winding, or capacitor, it will not start on low speed. If the motor is running on high speed, and it is switched to low speed, it may continue to run but may overheat since it is weaker without both windings. It is curious that the low speed has a 25 mf capacitor. If you have the part number, it may still be in the system to check."

Inyopools  Posted: 12/19/2016 17:06 PM  Inyo Product Specialist

SwampPool - See answer to Sean B comment.

Inyopools  Posted: 12/19/2016 13:44 PM  Inyo Product Specialist

Sean B - Your motor should have at least a start capacitor underneath the back electrical cover. If it also has a run capacitor, it will be under a bump out on the top of the motor. If you have a leak between the pump housing and the motor, you will have to replace the housing gasket.

SwampPool  Posted: 12/17/2016 22:41 PM 

I have an in-ground pool that is about 18,000 gallons (using pool calculator) and my pool pump stopped working. The pump will start up and prime with water entering the pump and then it just stops pumping water and there is loud click noise that sounds like a switch or breaker inside the pump motor. The motor will “stay on” and make a humming noise. If I turn the pump off and then try to restart it, it will just hum and not “turn over” and the motor will heat up. The impeller turns freely so it is not jammed. I went to the pool store and they said I needed a new motor if I wanted to install it or I could just buy a new pump. I haven’t replaced the capacitor and I do not know if my motor has 2 or just 1 capacitors. Another thing I noticed was that when the pump is working for the first 30 seconds, there appears to be some water leaking where the housing attaches the motor. Check out this video I uploaded of the problem:

My current equipment: 1) Jandy Stealth Pool Pump JHPU 1.0, this exact pump is discontinued and I think it is an “upward” flowing 2) Emerson EB654 C Flange Pool Motor 1 HP – replaced original motor more than 5 years ago 3) 2” PVC pipe with Jandy Valves 4) Jandy cartridge filter 580

Any thoughts on what the problem is with my pump? Do I need a new motor? New entire unit?

GeorgeC  Posted: 12/17/2016 11:48 AM 

I have a two speed 220v GE spa motor, starts/runs on high, only hums on low but will run on low if switched quickly after running first on high. 2 caps, both "run" values, 25-30 mf. No start switch or starting cap found--makes sense, motor code KCP indicates permanent split cap. Question is, why are there TWO caps? Cannot find any wiring diagram with two run caps anywhere. One cap shows hi volts on high, 0 on low; other cap = 0 no matter if running high or low. Want to understand-is driving me nuts! Thanks, GC

Sean B  Posted: 12/16/2016 15:55 PM 

My pool pump motor will start and will work fine for about 20 seconds. Afterwards, it clicks and stops pumping water and then it hums until kill the breaker. If I immediately try to restart the pump, it doesn't spin and just continues to hum. I don't know if my replacement motor, Emerson EB654 C Flange, on my Jandy Stealth JHPU 1.0 pump, has 2 capacitors or just one. Other troubleshooting info is that it appears to leak water in between the motor and pump. Please check out this video I posted on YouTube of my pump not working.

Inyopools  Posted: 12/12/2016 10:28 AM  Inyo Product Specialist

pump/timer issues - It sounds like your timer isn't supplying power to the pump. Check the output power on the timer. See Steps 2 and 6 in our guide on "How To Use a Multimeter to Test a Pool Pump Motor - Voltage". If your pump is set up for 115V, you would see 115V across terminals 2 and 4. Then check that your timer is wired correctly. See our guide on "How To Install an Intermatic T104 Timer". This guide is for a T104 timer for 220V. If you have a T101 timer you would check for 115V across the 2 and 4 terminals.