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

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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

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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.

Comments

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(1 to 40 of 170)

 Posted: 4/7/2019 

My pool motor runs during a quick bench test. But there is no re-action when it is installed on the pump. I measured 220v at the input. I have a Sta Rite Pentair pump and USQ 1152 motor. My next guess is the bearings but I can't understand why there is no noise and no movement at all when it is installed on the pump.
 Reply

InyoPools Product Specialist  Posted: 4/8/2019 

Joe - have you checked that the impeller and the diffuser are not blocked or locked up? Is there scoring on the impeller, diffuser, or seal plate which might be a sign of rubbing?
 Reply

 Posted: 4/8/2019 

There is 220 VAC at the input. But still nothing, no noise , no struggling, no hum, There is one thing different when testing on the bench. I didn't want to play with 220v so I switched the control knob to 115v just for the bench test. Then I turned it back to 220v. But I get no reaction when the motor is installed on the pump.
 Reply

InyoPools Product Specialist  Posted: 4/9/2019 

Have you tried applying switching the motor to 115 and applying 115-volts to the motor when it is installed on the pump?
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 Posted: 4/10/2019 

Thank you for the follow up. Today I turned the AC switch to 115 VAC while the motor is installed. And it tried to run. It sounded almost normal with 115 vac. It was trying to run the pump. The AC switch is very difficult to turn and I'm concerned about breaking it. So, does this new indication mean that the AC switch is bad or could it be the motor wingdings? Maybe I can wire the 220 vac directly and bypass the black control knob. What are your thoughts?
 Reply

InyoPools Product Specialist  Posted: 4/11/2019  Latest

I sent your question to a senior Century Motor's technician, and received this reply:If the motor is tested on a bench with no load, it will start if 115 volts are applied, regardless of the setting of the voltage change device.  If the power supply to the motor is checked across the two leads, it would read approximately 115 volts if that is the power supply.  If the power supply is approximately 230 volts, that would be the reading between the two leads.  If the power supply is approximately 230 volts, and the motor voltage change device is set to 115, the motor will burn out immediately. If the voltage change device is set to the voltage being applied, even if the pump was locked up, the motor would attempt to start, and then trip the internal overload.  After it cools down, it would attempt to restart.  The voltage change device is not easy to turn.  A wrench is the best way to rotate the device, while holding the terminal board with the other hand, so it doesn’t break. Is this a new motor that is being installed, or an existing motor that has a problem?
 Reply

 Posted: 4/8/2019 

The diffuser is brand new and the o-ring is brand new with Magic Lube. The PS-201 seal is also brand new and so is the starting capacitor. The impeller is clean and fine. The motor runs during a bench test but there is no action when it is installed.
 Reply

 Posted: 3/29/2019 

I have a Hayward pool pump mod # UST1102. The pump has been off for a couple of months. I turned it on and then looking through the cover, I noticed there was no water in the pump container. I shut off it off and filled the container with a hose. I turned the pump back on, and nothing... No noise, no hum and no pumping.
 Reply

InyoPools Product Specialist  Posted: 4/1/2019 

Hello  Tom - have you checked the pump circuit's voltage? This will determine it is getting enough electricity to run. Also, depending on how long your pump ran dry, your motor may have overheated and needed time to cool down. I would give it 15 minutes to a half hour and then give it another go. If after the motor cools down, and it still will not turn on, and the voltage is normal, the motor may need deeper troubleshooting.
 Reply

Anonymous  Posted: 3/27/2019 

My motor makes a buzzing noise and won't turn on. I can turn it with a screwdriver on the tail end of the motor without any problem, assuming it wasn't rusted inside? Do you think the capacitor, likely the problem? Also do you guys sell the capacitor cover with the screws for an Emerson EB841? The guy who came to give me an estimate broke the cover and the screws to open the cover. And quote me $900 to change the motor. If its problem is only the capacitor, then it will save me loads of money. But will have to find a way to extract the broken screws and find the replacement cover.
 Reply

InyoPools Product Specialist  Posted: 3/28/2019 

It very well could be a bad capacitor. For information on how to check it, read this guide: How to Test a Pool Pump Capacitor.
 Reply

 Posted: 2/15/2019 

Hi. My motor will not always start. When it will not start, if I give it a little turn with a screw driver it will then run fine. I replaced the start capacitor. What should I check next?
 Reply

InyoPools Product Specialist  Posted: 2/18/2019 

Hello James - Have you tested the circuit's voltage? Has the motor gotten noisier recently, like a grinding noise?Do you have the part, catalog, or model number from the motor label? Just want to determine which motor we're discussing.
 Reply

 Posted: 2/12/2019 

Hi I ordered a new pump motor from you guys last week (Order #917261) and replaced the old pump motor with the one you sent me. When I go to turn the pump on, nothing happens, at all. I checked with a volt meter to make sure I am getting electricity to the motor and verified that I am getting power. But like I said, literally nothing happens at all. Timer is on as well as all breakers. Any suggestions?
 Reply

InyoPools Product Specialist  Posted: 2/13/2019 

Hello Joseph - The motor is set at the factory for 230v. Are you supplying 230v or 115v to the motor?
 Reply

 Posted: 2/13/2019 

Hi Robert, yes the motor is switched to 230v and that is the power I am supplying.
 Reply

InyoPools Product Specialist  Posted: 2/13/2019 

You ordered the B2853. This is a 1HP uprated motor with a total HP of 1.25. If the old motor was the same rating, you may have a defective new motor. If the old motor had a higher total HP, the new motor may have burned up attempting to run. Either way, call our customer support at 407-834-2200. They can initiate the replacement process.
 Reply

 Posted: 1/31/2019 

I have a weird problem i can't pin point. I got this spa for free awhile back and have since been replacing parts to get it to run right. I don't know the brand or model, but the circuit board is a spabuilders one and there's a date of 07/2005 on the tub itself, so it is quite old. I have gotten the tub to cycle and heat up fine, but when the motor is running on high, the motor itself shuts off after a few seconds of running. I tested for power and it is still receiving power from the relay when the motor shuts off so i would assume that my issue has been something inside the motor the whole time? The only thing i replaced on the motor was the starter cap because it never used to start from a stop when i got it. This happens throughout all temps of the motor as well. I have left the tub unplugged for a week so the motor is dead cold, (40f or so) and it'll still shut off and shut off faster when the motor is warmed up. Is there something inside the motor i could fix or replace or would I be better off replacing the motor as a whole? Thank you.
 Reply

InyoPools Product Specialist  Posted: 2/4/2019 

Hello Bailey - It sounds like it could be the windings. We would recommend replacing the motor. What is the catalog or part number of the motor?
 Reply

 Posted: 1/21/2019 

My pressure pump motor hums. I have changed capacitor but no change. I have turned the motor over by hand at motor end using screw driver and although it turned, it was not easy. It has been in place for almost 15 years so am I right in saying it's time to get a new one?
 Reply

InyoPools Product Specialist  Posted: 1/22/2019 

Hello Stel - The fact that it's hard to turn by hand and that a new capacitor didn't work, signifies that a new motor is likely needed.
 Reply

 Posted: 1/13/2019 

My pump shut off this morning after running just fine. The breaker for the pump in the breaker box near pump and the main house breaker box pool equip breaker both tripped for the pool pump. I flipped them back on, and they stay on, but the pump appears to be getting no power. Not sure what to do at this point.
 Reply

InyoPools Product Specialist  Posted: 1/15/2019 

Hello Steve - We would recommend using a voltage meter to make sure that power is getting to the pump motor. If it is, we recommend replacing the motor. If not, we recommend contacting an electrician to diagnose the problem.
 Reply

 Posted: 1/9/2019 

My pool pump motor is not coming on during the auto programming. I can put it in service mode on the main panel and use the control on the top of the pump and it works. Do you think there is a problem with the main panel causing the pump not to engage during the normal programmed settings?
 Reply

InyoPools Product Specialist  Posted: 1/10/2019 

Hello Todd - What is the make and model of your pool pump motor and control system?
 Reply

 Posted: 11/1/2018 

I have a Jandy RS4 system. My filter pump won't start from the remote unit, but will start from the power panel when the unit is in service mode. Since it starts at the local button, does that rule out the relay? Should I be troubleshooting the remote unit and the board? Thanks for any help.
 Reply

InyoPools Product Specialist  Posted: 11/2/2018 

Hello Matt - You are correct. It doesn't sound like a relay issue. We would recommend looking at the board and remote/receiver.
 Reply

 Posted: 10/31/2018 

I have a US Motor 1081 Polaris Booster pump. It recently began to not startup when power was on. But when I spin the shaft, it starts and runs fine. It does this with the 370v, 35mf run cap connected and disconnected. I connected a 125v start cap to it and it starts up but it makes noise. It's not not the right size but would this indicate that the run cap also functions as a start cap and that it is bad?
 Reply

InyoPools Product Specialist  Posted: 10/31/2018 

Hello Sklemetti- Your problem could be a defective run capacitor. You can rule out the capacitor by testing it with a multimeter. Check out our article titled "How to Test a Pool Pump Capacitor". If the capacitor checks out ok, your problem could be a phase winding. If that's the case, the motor should be replaced. The replacement motor for the Polaris Booster Pump is part number B625.
 Reply

 Posted: 10/3/2018 

We left the area before the hurricane and turned off the swimming pool motor. Upon our return the motor just hums but does not engage the pump. We have checked for debris etc., Is here anyone in the Clarkton NC or Elizabethtown NC that works on swimming pool equipment. We need help! In addition to the present problem we also need new plastic pipes and other parts of our equipment replaced.so although getting the pump started so we can clean the pool we will need to purchase some equipment. Kerry Baidin kts@gmx.se
 Reply

 Posted: 5/8/2018 

Hello Patti - We could not find your order in our system. What motor did you order? Are you supplying 115v or 230v to the motor? Have you tested the voltage to make sure power is getting to the motor?
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 Posted: 5/7/2018 

I replaced the motor and still will not start. I bought new motor last week from you. any suggestions?
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 Posted: 5/2/2018 

Thanks for the reply. I was thinking it was the relay, too. I was only doubting it because everything I found online indicated that when relays fail, they get stuck shut, meaning that the pump won't shut off. I couldn't find any case where the opposite was true, but I'm guessing it's possible.
 Reply

 Posted: 4/30/2018 

Hello Jeff - It sounds like the relay is the problem. You can also check the connections at the relay. Sometimes the lines will get loose and it can cause the motor to run intermittently.
 Reply

 Posted: 4/29/2018 

My pump won't start unless I whack the control panel on the wall with my hand. Then it might run continuously, or might start and stop intermittently. Is there something inside the control panel that might need to be replaced. I have read online about bad relays, but not sure what to look for.
 Reply

 Posted: 3/9/2018 

Found the culprit: I pulled the motor apart and found a very thin 1" ring lodged between the windings and the housing. It must have fallen off the back of the end bearing into the motor when I pulled the shaft for the bearing change. The ring wasn't listed on the drawings of the motor, nor did I see it in the motor when I put the shaft back in. I suspect that it has been moving around in the motor causing the intermittent failure. Pump started straight away once I had it all together and hooked up again.
 Reply

 Posted: 1/19/2019 

Wow..perfect description of my problem. I replaced the bearings, seals and impeller with the pump running fine for couple years. It is now doing the exact same thing as yours, intermittently tripping the breaker! I will let you know if this little ring (aka.culpret) is my issue ..or will be asking if there are other potential remedies. Thank you.
 Reply

 Posted: 3/8/2018 

My 3 year old 1hp Certikin pump was running without any issues until the bearing failed. I replaced the bearings and the water seal myself and the pump was turning smoothly. Now when switching the pump on, sometimes the breaker trips immediately, sometimes the pump runs for 5 to 10 seconds before the breaker trips while other times it just runs fine and does so for many days switching on and off on the timer until the breaker trips again. Once the breaker has tripped I need to reset it sometimes once, sometimes more times for the pump to start but when it finally runs, it keeps running fine, it doesn't trip. This morning after cleaning the pool, switching the pump on/off various times, the pump now keeps tripping the breaker. I live in a warm and dry climate, the pump is dry hence moisture is not likely to be a possible cause. Any suggestion what may cause this is much appreciated. Thanks.
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 Posted: 11/9/2017 

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
 Reply

 Posted: 10/31/2017 

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.
 Reply