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Old 09-28-2022, 07:21 PM   #1
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Shurflo Pump Pulsing

Hi Folks,
I found my pump running and the faucet was closed.
The motor was hot.
I let it cool off.
Now the pump is pulsing when the faucet is open.

I have an accumulator.
When I increase the pressure, the pulsing goes from slow to quick.

I tried lowering and increasing the pressure screw, not the bypass.
Doesn't seem to have any affect.

Could it be air in the line?
Could the motor be damaged?

Also, I've seen videos where the pre-filter cover is on the bottom and on the top.
What it the correct orientation?

Any suggestions would be greatly appreciated.
Thank you.

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Old 09-28-2022, 07:30 PM   #2
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We had a weird problem where the pump would run even though the faucet was closed. I couldn't figure it out but I looked online and found that this is an indication of a faulty pump switch. It's not all that uncommon after a while of use. It screws right on the top of the pump, where the 2 red wires clip on. It cost like 20 bucks and took like 10 minutes to replace. Instructions were included with the switch.
Super easy fix. Its possible that that's the problem, and even if not its probably not a bad idea to order another switch as a backup.
Our pre-filter has the screw-on clear cover oriented on the bottom.
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Old 09-29-2022, 11:51 AM   #3
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Thanks Drew Bru.

The original problem was that the switch burned out.
We replaced it with the same model number switch.
But while we were waiting for a time when we could pull out the switch and get the model number, we bypassed the switch with a dc light switch.
One day I forgot to turn off the switch after I turned off the faucet and the motor ran until I noticed it.
Could have been an hour or so.
After it cooled off, It seemed to run fine.
After we installed the replacement microswitch, the motor pulses between high and low pressure.
I recalibrated the pressure (9 1/2-10 turns) and bypass (10 1/2-11 turns) screws and the pressure in my Accumulator (30 psi).
I've tried varying the pressure screw, but it seems to have no affect.
I noticed that if I over pressurize the accumulator, the pulsing becomes more rapid.
I'm thinking that either the motor is damaged or the pressure switch height or functioning of the switch is a little off, and might be the cause.
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Old 09-29-2022, 12:37 PM   #4
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I'd be captivated to learn if someone knows if water could cavitate under the stated conditions.
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Old 09-29-2022, 03:12 PM   #5
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Captivating and cavitation on one post...right on!

I also had the switch thought...but, if that's not it I would check the valve on the input side of the pump. That one-way check valve prevents (or is supposed to) water pressure from leaking back towards the tank. If that valve is leaking, due to debris or a torn seal, the pump will act as if there's a valve open downstream. Increasing the accumulator pressure like you did would make the leak-back faster, which would cause the pump to cycle faster to keep up with the leak. So, that's my guess.
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Old 09-29-2022, 05:05 PM   #6
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thank you rossvtaylor!
i think we will order a second one to have on hand while i to do some surgry and comparing to the first one.
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Old 09-30-2022, 11:21 AM   #7
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Quote:
Originally Posted by rossvtaylor View Post
Captivating and cavitation on one post...right on!
And left off! 🥸
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Old 10-05-2022, 06:52 PM   #8
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Your accumulator should have a bladder or air space in it. Water is non compressible so air cushions the system stops pulsing.
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