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Old 07-25-2013, 02:20 PM   #1
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Fresh water pump stays on

Suddenly a couple of days ago, the potable water pump stayed on, instead of cycling off a few seconds after turning off a tap.

The pump is a SureFlo 4901. I can buy both a switch assembly, or a valve assembly, for it (around $50 each). Or I can buy a new pump.

The water tank is full. The system holds pressure when the pump is off, so I don't think it's a leak.

Before I buy a new switch or whole new pump, does anyone have any other troubleshooting steps?

Thanks!!
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Old 07-25-2013, 02:50 PM   #2
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Does your system have an accumulator tank?

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Old 07-25-2013, 03:17 PM   #3
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Does your system have an accumulator tank?
No. It's pretty extensive (galley, 2 heads with showers, 11G water heater, outdoor washdown spigot) so the whole system seems to absorb a lot of pressure spikes.
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Old 07-25-2013, 03:35 PM   #4
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You either have a on demand water pump or one that incorporates an accumulator tank like the ones you see hooked to the hot water tank at home. So if you have an accumulator tank it may have a ruptured bladder.
Images of accumulator.

If you have a pump that pressurizes the lines from the pump to the appliance that is one thing.
Unless the tank that holds the water is closed and able to be pressurized. They usually don't. They have an air vent.

I would say it is the accumulator tank that is the culprit.

They are not expensive or hard to install. check Home Depot or Lowes
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Old 07-25-2013, 03:41 PM   #5
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Is there water coming out of the T&P valve on the water heater? That might indicate that the pressure valve is not functioning. Do you have a pressure guage on the line after the pump? What pressure does it indicate? Does the pressure reach the cutoff point of the pressure switch? If the pressure is low, maybe the pump has some debris clogging the impellor?
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Old 07-25-2013, 04:11 PM   #6
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I have this model, no accumulator tank:


No visible water leaks anywhere. No sound of running or dripping water anywhere. No sign of a slow leak (like the pump cycling) before this symptom. No noticeable loss of water pressure with the pump off for a while (10-15 minutes). I'll be going down to the boat to check how it did overnight soon. No pressure gauge anywhere in the system, but with the pump on I get the same strong flow I always get.

I'll check again, but I think I ruled out any loss of pressure downstream of the pump. That's what led me to wonder if the pressure switch itself may have failed closed. But I never had that happen before, so I'm still open to other suggestions.
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Old 07-25-2013, 04:46 PM   #7
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The image didn't come through. I googled the pump you indicated in your first post.

Smart pump. Sounds like it got dumb

Replace or repair.

Sd
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Old 07-25-2013, 07:01 PM   #8
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Yup, it's repair or replace. After 24 hours of sitting with the pump off, I still had pressure in the system when I turned on the taps. So no leaks. Not sure why the image didn't show, it works for me. It's just a URL I found on a vendor web site using Google images.

Here's the parts diagram:


And a link to it if that doesn't work

I wonder if it's worth trying to swap out the switch assembly (1). I mean, the pump part obviously works. Or could the "valve assembly" (3) be bad? I've never had one of these apart.
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Old 07-25-2013, 07:13 PM   #9
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There might be pressure on the system, but is it getting up to 45 psi? If it is not, then there is something wrong with the pump that is preventing it from reaching the cut-off pressure. If the system pressure is exceeding 45 psi, then your pressure switch is failing. Seeing as it is an all-in-one unit, you are probably looking at replacing it.

So, tear into the current pump, and see if you can see any issues, worst case, you will be replacing the pump.
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Old 07-25-2013, 07:15 PM   #10
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Another thought, check the port going into the pressure switch to make sure it is not clogged.
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Old 07-25-2013, 09:27 PM   #11
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Quote:
Originally Posted by skipperdude View Post
The image didn't come through.
Quote:
Originally Posted by CaptTom View Post
Not sure why the image didn't show, it works for me. It's just a URL I found on a vendor web site using Google images.

Images linked by URL from third party sites (as above) or places such as Photobucket etc do not always load reliably depending entirely upon the page load speed of the viewer(in this case SD). It is one of those techie things that whilst I can apprehend the concept behind will never fully comprehend the meaning of. Our top dog "IT Guy" coworker of mine has explained it to me on more than one occasion so I'm just hopeless
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Old 07-25-2013, 10:58 PM   #12
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Agree with Theran, Your need to know the pressure to fault find. Is there anywhere in the system where a pressure gauge can be installed?
If not then its just trial and error. Either a plugged sensing port or a bad switch. Pull the switch off and check for any debris. Looks like there is a diaphragm in there that might be worth checking, too.
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Old 07-26-2013, 06:48 AM   #13
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I solved a similar problem by closing the valve to the hand pump faucet in the aft head. It seemed to have been sucking air through the faucet thus not building up pressure in the pump. The gasket in the hand pump may have dried out (I haven't taken the time to investigate) allowing air to be sucked past it. It took a lot of trial and error to solve that one.
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Old 07-26-2013, 07:11 AM   #14
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On some pumps the middle screw on the pump is a pressure adjustment...if you turn it most of the way(check instructions for which way...may have to go to manufacturer online) and can get it to stop...then I would just replace the pressure switch....

What I would normally do...unless I already have a spare is take that pump out...replace it...take that pump home and play with it under controlled conditions...If I could repair it I now have a spare or a motor for another use,.
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Old 07-26-2013, 11:38 AM   #15
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For a simple pressure guage, go to HD, in their lawn irrigation department, they will have a pressure guage designed to fit on a hose spigot. You can attach this guage to your wash down hose spigot.
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Old 07-26-2013, 01:09 PM   #16
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Psneed has the right idea I think. I just ordered a new one. I can use the system by manually cycling the old one until that comes in. Then swap them out and take the old one home to test and fix at my leisure. Assuming I get it working, I'll have a spare for an easy swap-out next time.

Theran, thanks for the tip, I'll head over to HD later and see if I can pick up a pressure gauge.
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Old 07-26-2013, 05:40 PM   #17
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Psneed has the right idea I think. I just ordered a new one. I can use the system by manually cycling the old one until that comes in. Then swap them out and take the old one home to test and fix at my leisure. Assuming I get it working, I'll have a spare for an easy swap-out next time.

Theran, thanks for the tip, I'll head over to HD later and see if I can pick up a pressure gauge.
When our pump go out I replace them. They last for about 7 years. I buy the low pressure 30 psi as they are easier on the old piping and do not waste as much water. In the winter they turn the water off for weeks, so you want to conserve water.
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Old 07-27-2013, 08:06 AM   #18
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When our pump go out I replace them. They last for about 7 years. I buy the low pressure 30 psi as they are easier on the old piping and do not waste as much water. In the winter they turn the water off for weeks, so you want to conserve water.
The replacement parts (valve or switch) each cost about 1/3 the price of a new unit. That makes repair a losing battle on something with a limited lifespan. I suppose the manufacturers know that. They would rather sell a new pump than have the customer fix the old one. That strategy worked on me.

I went with the same capacity as the old one, 4GPM and 45PSI. Maybe that's a little bit overkill. Still, with three sinks, two showers and an outside spigot, I didn't want to go cheap on this component.
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Old 07-31-2013, 08:34 PM   #19
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Make sure there is no debris in the valves and lubricate the micro-switch. It's a good idea to keep a spare pressure water pump aboard.
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Old 08-03-2013, 06:58 AM   #20
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Follow-up: The new pump went right in, we have water again! What a pain having to turn the breaker on & off whenever we needed. Not to mention forgetting to turn it off when we left the boat on a mooring for 3-4 hours.

The old pump is back on the workbench shoreside, to be refurbished as a spare. My best guess now is that the valve assembly (see diagram, above) needs to be replaced. It was only getting up to 20 lbs or so of pressure by the end there. Good tip on the $10 garden-hose pressure valve from Home Depot, I'm keeping that on board!
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