pressure switch fail?

wsconner

wsconner

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Jan 9, 2020
55
J J/42 1 New Castle NH
Not sure how to diagnose a pressure switch failure in my water system. I have an accumulator tank and jabsco series 36800-1000 pump. Once the system is pressurized, the pump slowly turns every now and then, like it's trying to slowing increase the pressure. At the same time this happens, I think I am getting a short on my DC panel (because the voltage meter drops like the DC leg of my panel is losing all power. Anyway, before I start rebuilding/replacing, figured I'd ask this knowledgeable group. Video of symptons posted here: IMG_1784.MOV

Many thanks
 
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dlochner

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Jan 11, 2014
11,432
Sabre 362 113 Fair Haven, NY
The DC voltage is dropping because the pump is struggling to pump. Electric motors take a lot of current for a few seconds to start up and then the current load drops and the pump runs smoothly. Your pump isn't doing that, it is drawing a lot of current, turns over once and then starts to draw a lot of current.

When you turned on the faucet the pump should have started running much faster, it didn't. So, I don't think the pressure switch is the primary culprit. The problem may lie with the pump itself, what is causing the pump to struggle? Is the pressure in the tank too high? Is the pump seizing? How does the pump run if you disconnect it from the accumulator tank? With no back pressure the pump should run smoothly and fast.

Try disconnecting the pump from the tank. First turn the power off, disconnect and have a helper turn the power back on. It should run fast. If it doesn't then the pump mechanism may need to be rebuilt or the whole unit replaced.
 
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Ken Cross

Ken Cross

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Oct 24, 2010
2,405
Hunter 30 Everett, WA
From your description it sounds like your pump continues to run after the pressure is up. This certainly should draw higher current which would make your battery voltage sag. As a test run the pump with a tap partly open. Now the voltage should be more stable. Keep in mind that all loads droop voltage depending on how much current. It sounds like your pressure switch failed. The pump should be running or off. None of this slow speed stuff.

Ken
 
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Benny17441

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May 24, 2004
7,131
CC 30 South Florida
I watched the video and the slow stream of water coming out of the faucet could indicate a blockage in the accumulator or the line leading to that faucet. Are all the other faucets that slow? If they are, try bypassing the accumulator and see how the flow of water is and how is the pump running. That pressure switch opens the flow of water at 20 PSI and closes it at 40 PSI. At those pressures you should have a healthy flow out of the faucets. If bypassing the accumulator shows no improvement I would then look at the electric motor which could also explain the steep rise in voltage draw. How old is the pump? Electric motors through use can wear down the bearings allowing the Armature to rub against the Fields and that friction will make the motor run slow and require much more power to start turning. You may also check the motor first by disengaging from the pump and spinning it by hand, it should turn freely with no noise. If the motor turns freely then activate the pump by hand looking for any stiffness or resistance to operate smoothly. Do the same with the transmission pulleys. If all checks out then the pressure switch is bad. Jabsco should have parts for that pump and once you determine the component at fault then it should be a matter of replacing that part. That clicking is what has me thinking, I don't know if that pump has some sort of safety switch to protect the motor in case of overload. see if you can find an Owners Manual online that would describe the operation and features. Good luck.
 
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wsconner

wsconner

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Jan 9, 2020
55
J J/42 1 New Castle NH
Thanks all for the sage advice thus far. I think I have a few trouble shooting steps I hadn't thought of before. A bit more context in case it helps... this started with fixing a leak in my hot water tank fittings (a bear to access). I've never really had good water pressure in any of the faucets, and just assumed it was that leak - if I left the pump on, it would cycle every 60-70 seconds (at what I think is full speed), so we only turned the pump on when we used the water. I assumed fixing the leak would increase the pressure, but it did not, and also created this new symptom of "slow pump". When this first happened, my accum tank (new) was at factor pre-set of 20psi, and the "slow pump" was happening every 10 seconds or so. I dropped the pressure in accum tank to 10psi and the symptoms abated to once every 60 secs or so. The manual for the pump doesn't state what the pressure switch is set to, but the accum tank manual says most pumps are set at 17-20 and the tank and pump pressure should match. So I'm going to assume 20 and reset pressure in the accum tank.

The pump is original to boat--25yrs and doesn't look like it's been rebuilt, so maybe I'm just dealing with a worn out pump. Will advise on what I learn...
 
JamesG161

JamesG161

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Feb 14, 2014
7,423
Hunter 430 Waveland, MS
Do you have the make and model number of the Accumulator?

Most have a flex bladder that can crack and leak.

Sounding more and more like a slight drip/leak of water.
Jim...

PS: I had same problem and found my Air fill valve on the Accumulator was drip/leaking.
 
wsconner

wsconner

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Jan 9, 2020
55
J J/42 1 New Castle NH
JamesG161 said:
Do you have the make and model number of the Accumulator?

Most have a flex bladder that can crack and leak.

Sounding more and more like a slight drip/leak of water.
Jim...

PS: I had same problem and found my Air fill valve on the Accumulator was drip/leaking.
Click to expand
Jabsco 18810-0000. It's brand new, so hoping tank is ok.
 
JamesG161

JamesG161

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Feb 14, 2014
7,423
Hunter 430 Waveland, MS
A test of the reserve pressure volume.

1) Close all outlets
2) Turn on water pump till it stops.
3) Turn off DC power to pump.
4) Open galley sink valve and collect all water in measuring cup.

That is your reserve volume of water.;)
Jim...
 
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dlochner

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Jan 11, 2014
11,432
Sabre 362 113 Fair Haven, NY
When it is time to replace the pump, (maybe today? :)) you do not need to replace the pump with a $500 Jabsco pump. This pump from Aqua King will do just fine, unless multiple faucets are open at the same time. This is a Defender Link, I'm sure the SBO store can also provide one, I couldn't find it in the SBO store. For $100 it may not be worth trying fix the existing pump.

www.defender.com

SHURflo Aqua King II Fresh Water Pump

Shurflo fresh water pump Features: Unique over-molded single-piece diaphragm assures a long life and top performance in all plumbing systems Designed as the next legendary pump to exceed the expectations of customers, this pump is constructed for
www.defender.com www.defender.com
 
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MitchM

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Jan 20, 2005
1,021
Nauticat 321 pilothouse 32 Erie PA
ah, it's so good to see the old belt drive fresh water par jabsco still working a, lbeit a little slowly. i have that pump and it needed a 'rebuild kit' after a mere 35 years of sevrice. couldn't hold presure, performed erratcally. call par jabsco, humans answer the phone . read them your serial no. so you get the right rebuild kit. i did NOT run my PJ freshwater pump w an accumulator, they had advised against it. my ParJabsco fw and bilge belt drive pumps are still going strorg now in 2020 -- 40 years after their build dates. and did i mention the pj bilge pump is a remote-mount, high and dry above the slimy bilge, and lasts a very very long time ?
 
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capta

capta

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Jun 4, 2009
4,773
Pearson 530 Admiralty Bay, Bequia SVG
First thing I would do is remove all the hoses from the pump and see if it runs up to speed. If it does, it's not the motor. If it doesn't it's most likely the brushes, easily and cheaply replaceable, if you know how to clean a commutator and reassemble the motor. Not complicated, but holding in the brushes when reinserting the armature can be finicky. Motors are easily and cheaply available on EBay. Those pressure switches rarely go bad, but they just screw into the base, so replacement is easy. I always carry spare valves, a belt, diaphragm and pressure switch. Lastly there is a rubber diaphragm on the end of the pushrod from the motor. A hole in that will pretty much disable the pump.
Since there are 2 valves in the pump (cheap and easy to replace) check to see if one is broken or has a piece of grit, hair, etc in it, because that will stop the flow. Take note of which valve is up or down (take pics as you disassemble). Check to see the bearing from motor to pushrod is turning easily; it could simply be a corroded bearing that is putting resistance into the drive system. If the valves are good and everything else checks out with the pump, move on to your water system.
I have half a dozen of those of various sizes and they are the best pump on the market. Since parts are available and they are so reliable (our bilge pump, 34600, is 40+ years old) and easy to fix, it would be madness to replace it with the new stuff with built in planned obsolescence. But if you decide to get a newer pump, please let me know as I'd like the old one. I have yet to get one from someone I couldn't repair for $100.00 or so, and most for under $30.00.
 
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odaydokay

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Jul 5, 2011
702
Oday 28 Madison, CT
This is probably not the issue, but assume you have pulled off and cleaned the pump strainer or filter located between the water tank and pump?
 
wsconner

wsconner

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Jan 9, 2020
55
J J/42 1 New Castle NH
odaydokay said:
This is probably not the issue, but assume you have pulled off and cleaned the pump strainer or filter located between the water tank and pump?
Click to expand
yes, good call out, but the filter is fine. I've got a few small leaks I'm still chasing that I want to fix before I troubleshoot the pump itself. I just need to be miniaturized to be able to fit in such small spaces!
 
capta

capta

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Jun 4, 2009
4,773
Pearson 530 Admiralty Bay, Bequia SVG
wsconner said:
I just need to be miniaturized to be able to fit in such small spaces!
Click to expand
LOL Bradford Marine in Dania used to (may still have?) a midget (or little person if you prefer) on the payroll. That guy could get into places most of us couldn't even get our hands into. He was very well paid, and worth his weight in gold!
 
wsconner

wsconner

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Jan 9, 2020
55
J J/42 1 New Castle NH
so I figured out what was going on with the pump--not that I entirely understand it. I removed one of the three batteries from my bank to get access to hot water tank (and fix the leak), I left a ground to the bus bar disconnected (!!). So not sure I understand why it caused the panel to drop voltage when the pump was on, but when I reconnected that battery everything worked fine and I think I solved my leak problem.

I didn't really gain much water pressure though. This vid shows the pressure I have and after the system is pressurized, it takes 22 seconds for the pump to re-engage. Does that sound about right?

IMG_1791.MOV

drive.google.com drive.google.com
 
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dlochner

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Jan 11, 2014
11,432
Sabre 362 113 Fair Haven, NY
Water pressure will depend on the pressure in the accumulator tank, and indirectly the pump's pressure settings. A second factor is obstructions in the screen at the faucet, kinked or clogged hoses, or clogged filters after the tank.

One significant advantage to lower water pressure is that it reduces water consumption. Those of us on municipal water supplies at home can get used to high water pressures and don't worry too much about draining the reservoir.

Since the pump worked with the ground disconnected there must be some alternative path to ground, perhaps through the engine ground?
 
wsconner

wsconner

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Jan 9, 2020
55
J J/42 1 New Castle NH
dlochner said:
Since the pump worked with the ground disconnected there must be some alternative path to ground, perhaps through the engine ground?
Click to expand
Yes, negative bus bar in my system is grounded to the engine. Still not sure I understand why it caused the symptoms I experienced.
 
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