Pump motor humming and not starting with new capacitor

snmobley

Active member
Dec 10, 2018
39
Birmingham, AL
I’ve searched and have read several threads with what appears to be the same issue. I’ve tried everything I’ve seen suggested but no luck. Here’s what I’ve done...

- new start capacitor
- spun the impeller from the motor side using a screwdriver
- spun the impeller from the strainer basket side with my finger, it seems to spin fine
- tried tapping the motor with a hammer while humming

Any last minute suggestions before I have the motor replaced tomorrow?
 

wireform

Silver Supporter
In The Industry
Aug 15, 2017
486
Spring Valley, NY
Two things of note. If this is a 220 v pump, make sure that you have 2 hot legs all the way to the motor. Start at the circuit breaker and follow to the timer if you have one, to timer and from timer. Then check at the pump itself. There is also a switch in the back of the pump shaft to keep the capacitor alive until the centrifugal switch throws it out once it's running. Make sure the switch there is closed when the motor is in the off mode otherwise the capacitor isn't in the circuit and won't help the motor start.
 

wireform

Silver Supporter
In The Industry
Aug 15, 2017
486
Spring Valley, NY
Do a youtube search. You will see it. It basically stays closed keeping the capacitor in circuit to give the pump motor the boost to get going. Once running the switch opens up via centrifugal force as the motor doesn't need the capacitor at that point.
 

JamesW

TFP Expert
Mar 2, 2011
16,589
It's a V shape of two copper strips.

If the connection point is not making good contact, you can clean the contacts to see if that helps.


The switch has two parts. One part is the copper V and the other part is the centrifugal weights that swing out at full rpm.

When the weights swing out, the center drops down and the copper strips disconnect to take the capacitor out of the circuit.

You shouldn't have to remove the switch. Just try to clean the contacts. You can replace it if necessary.

When replacing the capacitor, make sure that the wires are back inside the stands and not where the centrifugal switch weights can hit the wires when they swing out.

How old is the motor?
 
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JamesW

TFP Expert
Mar 2, 2011
16,589
It's about 5 years old. Usually, it's the capacitor.
Did you use the exact same one for the replacement?
Check the switch contacts.
Check the voltage going to L1 and L2.
 

JamesW

TFP Expert
Mar 2, 2011
16,589
Maybe contact cleaner or light sanding.

You might want to get a new one in case it happens again.

Once the contacts burn, they tend to fail from arcing.

When reassembling everything, make sure that the wires are away from the spinning weights.

The weights swing out at full speed and can snag any loose wires.
 

JamesW

TFP Expert
Mar 2, 2011
16,589
If they do motor changes, they might have some old motors that you can pull one from if they don't have any new ones.

Sanding the contacts will get the motor operating again if you have to order a new switch.
 

snmobley

Active member
Dec 10, 2018
39
Birmingham, AL
James, thanks for all your help! So is the proper part name a “contact switch”?

Is this a likely scenario for what happened? Original capacitor goes bad but pump tries to keep starting for a while, maybe even hours, and then ends up burning up the contacts? I replace the capacitor but it has no chance of working because of the contact issue?
 

wireform

Silver Supporter
In The Industry
Aug 15, 2017
486
Spring Valley, NY
As James said, you can clean both surfaces but try to keep them as parallel to each other as the original surface so it will retain good contact. The way I do it is sandwich a piece of sand paper in strip form between the contacts, apply lite pressure and pull through. Don't complety clean one side and flip to do other one. Then go back and forth between the two. Make sure after reassembly that the spring loaded thingy on the shaft, moving it with your finger is putting pressure on the switch and that they close making contact. Usually you'll be good to go not needing a new swich. Picture does not look too bad. Have seen much worse. Have some out in the field running years after a contact cleaning.
 

JamesW

TFP Expert
Mar 2, 2011
16,589
Any time you open or close a switch, you will get some arcing when there is current flowing.

The switch might have stuck shut and burned the capacitor or stuck open from being burned. Hard to tell.

In any case, a new switch will likely get you operational.

Try light sanding. If you have some emory board, cut one into a thin strip, slip it between the contacts and sand.

 

snmobley

Active member
Dec 10, 2018
39
Birmingham, AL
No one in town had a new contact so I lightly sanded but no luck. I’m pretty bummed right now. Everything I’ve done I was like “this is gonna be it” but I’m still at square one.
 

JamesW

TFP Expert
Mar 2, 2011
16,589
There's a loose yellow wire that can get snagged by the centrifugal switch weights.

Get that tucked inside the stands that hold the capacitor or it's going to get ripped out.

Check the power connections. They look suspicious.

Check the voltage. What is the supply voltage?

After testing the voltage, turn off the power at the breaker, remove the capacitor and test the resistance from L1 to L2.

Make sure that the centrifugal switch is installed correctly and the contacts are closed.

Try a different capacitor. Maybe the new one is bad.

Did water get sprayed in the motor?
 

snmobley

Active member
Dec 10, 2018
39
Birmingham, AL
We have had enough rain to float Noah’s ark the past two days but the pump has been exposed to the elements for five years so not sure if there is any correlation from the recent heavy rain to the motor not working. I’m going to check the new capacitor whenever I figure out how to. My multimeter doesn’t have a capacitance measure.
 

wireform

Silver Supporter
In The Industry
Aug 15, 2017
486
Spring Valley, NY
You can have a humm even if the capacitor is good "IF" you don't have 2 hot legs all the way to the back of the pump. Did you check that you have L1 and L2 live. Maybe a wire slipped off the timer or something. Check line to line and line to ground. See what you get.