Fresh Water Pump Not Holding Pressure

[stormchaser]

I've got the original BIG Galley Maid fresh water pump (32v). It seems to leak down pressure. I cant find any leaks (as in dripping water), but it cycles on for about 1/2 a second every 20 seconds or so. It turns on around 20psi and off around 40psi (according to the gauge on the pump). It was rebuilt by Galley Maid about 18 months ago, just when we bought the boat. It's been doing this ever since we had the boat, but it's never been a big deal until now (this marina turns off water and we have to use the tanks). Thoughts?

 

[Angela]

You have a leak somewhere. Are your water inlets near your electrical hook ups capped tightly? That is a common source of water leakage that most people don't consider because they are looking for a leak inside. The check valves there tend to fail. Mine have and when I'm not using dockside water, those will seep just enough to keep the pump busy. It's hardly noticeable, but often the culprit. I have a tee with shut offs on my incoming pressure water connection outside the PH door. When I'm using the pump, I turn the shut off valve into the closed position.

If it's not there, you're going to have to start following the water lines and feel every connection until you come up with wet fingers. That will be a pain to do, but.... I once found a hose clamp that merely needed tightening and solved the leak. Given how not-so-old your rebuild is, I'm not suspecting a real problem with your pump at this point, but that's not to say that it can't be something in there. I don't suspect a stator because if your stator was worn out, you'd get nothing going - the pump would just sit there and run and run, never building pressure.

You could have a leak that does not necessarily result in a dripping noise, depending on whether the leaking connection is laying on something else or whether the water is quietly running down the hose/pipe, etc.

Check your dockside water hook-up first.

 

[Finalee]

That almost sounds like a bad accumulator tank. Check the tank pressure at the fitting in the top. Should read 10- 20 psi.

 

[Angela]

Oh yeah...I forgot about the accumulator tank, even though I have replaced mine! My GM tank is waterlogged. We added an external tank for something like $12 an left the GM waterlogged tank in place. I read somewhere that those tanks don't last long and are problematic which is why there is an external, household accumulator tank on our boat instead of fixing the expensive GM. Seems to work just fine for us.

But wouldn't a bad accumulator tank cause quick, repetitious cycling of the when it is in use? I got the impression Dave's pump was just losing pressure and then cycling, even when not in use. Perhaps, I just made that assumption since I was focusing on the pump not holding pressure. I don't think a waterlogged tank would cause a loss of pressure when there no demand for water, would it? Mine didn't - I found the waterlogged tank with quick cycling of the pump when a faucet was open. If that's your sympton, Dave, then yes, I'd suspect waterlogged accumulator tank for sure.

If it's not waterlogged, but just low on pressure, you can pump it up with a bicycle pump. If you find that you cannot push any air into the tank at all with the bicycle pump, then your tank is, indeed, full of water.

 

[Finalee]

The cycling for 1/2 second every 20 seconds is the odd part of the equation.

How long will the system hold pressure when the pump is off?

 

[stormchaser]

OK, don't want to sound dumb, but GM accumulator tank? I have a GM pump and it like like it is a pump on top of a pump or maybe a pump on top of a small tank. The mechanical pressure switch and gauge are connected to the lower unit (tank?). The pressure switch is all mechanical and cycles on and off as the pressure lowering/raising moves and eventually makes 2 sets of contacts connect. There is also a separate accumulator tank T'd in. See attached pics. Yes, it cycles on and off whether the water is in use or not. It ALSO periodically trips the circuit breaker. ??? Thoughts?

 

[stormchaser]

Oh, the inline check vales are not leaking, I just replaced them last week...HOPING it might be a cure for the pump running and for the tanks slowly getting over-filled when on dock water. It fixed the back flow into the tanks and overfilling them problem but the pump cycling remains.

I am thinking it is some sort of air leak, NOT a water leak, if that's possible or some sort of internal to the pump leak???...it cycles on FREQUENTLY, like for a very short burst (1/2 second) but does it every 10-15 seconds. Very annoying...

 

[stormchaser]

The cycling for 1/2 second every 20 seconds is the odd part of the equation.

How long will the system hold pressure when the pump is off?

Same amount of time if I turn it off. I really believe the pump is allowing water/pressure to go backwards to the tank...if that's possible? I can hear water rushing though the pump when it first turns off.

 

[stormchaser]

Whoa, wait a sec...check values...water/pressure bleeding back to the tank...is there a check-valve that prevents water/pressure from going back to the tank? If so, sold THAT be causing my woes? If you look at this pic, just to the left of the strainer is a small brass thingie...think that might be another check valve? Or does does the system keep pressure/water from back-flowing? A check valve in the pump?

 

[Trojan]

The brass fitting with the cap on top next to the strainer is a check valve.
Bill

 

[stormchaser]

So, I opened the cabinet to the rear tank and listened...water IS rushing back into the tanks when the pump cuts off...sound like that inline check valve is bad. Interesting, 3 check valves all go bad around the same time. they all LOOKED original. Humm...

 

[GJH]

I went through a similar drill about two years ago. There should be a check valve right by the tank and one at the end of the pump.

 

[Angela]

Well..there is your leak! One more check valve and it sounds like you should be back in business.

 

[SKYCHENEY]

While you're at it, you might want to check your pressure in your pressure tank. It should be set the same as your cut-in pressure of your pressure switch. Drain the system down and put a gauge on the tank.

 

[stormchaser]

Check valve replaced and the pump has not come on in the past hour! Yay!!!!

 

[Walter P]

I can't believe it was that simple. My 48 (1982 Series I MY) has had a similiar problem for a few years and it's been driving me crazy (a very short trip in my case). I replaced everything from the pickup to the water pump twice and I still had a problem. Frustrated, I even spent a couple of boat bucks to have the job "professionally" done, all to no avail. It's amazing that no one ever mentioned the check valves before. Thanks guys and gal for the information, I can't wait to get back to the boat and try it out.

Walt

 

[stormchaser]

Still has not come on even once unless a faucet was open! Yay! Finally!

 

[kwerges]

Okay, not to hijack the thread, but my freshwater pump cycles when I turn on a faucet, etc. Just started doing this recently. Confirm this is a waterlogged accumulator(?), and what exactly does that mean???

 

[GJH]

See what the air pressure is in the tank first; a common tire gauge is all that's needed, and a bicycle pump if you need more pressure, which should be set just below your pressure switch cut-in point. If it won't hold pressure, it is likely water logged and needs to be replaced. What type of tank do you have?

 

[Trojan]

The last check you changed is the most important one.

All pumped water systems require an accumulator tank. The acum tank must be always about half full of air. This creates a cushion in the system. Since you can not compress water the air is used. If you look you will see a pressure switch. It has a diaphragm and a spring loaded switch that starts and stops the pump at a set set of high and low pressure points. Once the air is gone from the tank you loose the cushion and the pressure switch stops functioning as a pressure regulation switch and it operates just as an off and on switch. The loss of this air cushion in the tank is what people call a water logged tank. Adding air back into the tank will restart the pressure regulation curing the water logged tank. You must turn off the pump and drain some water from the tank at the same time inducing air. Or if you have the bladder type tank you can just add more air when the pump is running. Bladder pressure should be set just under the start up pressure.

BILL