Jabsco Main Fresh Water Pump constantly running

May 18, 2017
66
Hunter 44 Changes
I'll be replacing the original Jabsco Sensor Max 14 Fresh Water Pump, model 31750. It is running constantly even when all faucets are closed. It only shut off at the breaker. When the breaker is switched on, the pump immediately starts running loudly without an open faucet. I'm curious as to your thoughts on the best replacement for it. I had good luck with Jabsco. It's sensored controlled; 35 PSI.
 
Feb 20, 2011
7,990
Island Packet 35 Tucson, AZ/San Carlos, MX
Just spitballin' here, but did you check the check valve?
 
May 18, 2017
66
Hunter 44 Changes
No, I have not disassembled it. At 13+ years old (the original), thought best to replace it although good suggestion. Perhaps I'll inspect once I remove it. Murphy's Law - happen the night before I was packing to head out-of-town. Not much time for thorough trouble shooting.
 
Jan 12, 2011
930
Hunter 410 full time cruiser
Is it pumping water???? I know it sounds silly, but ................................
 

Johnb

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Jan 22, 2008
1,419
Hunter 37-cutter Richmond CA
My perfectly good fresh water pump will run forever if the tank runs low to the point where it sucks air. Once that has happened you have to fill the tank and then open a faucet for it to prime.
 
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May 7, 2012
1,338
Hunter e33 Maple Bay, BC
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May 18, 2017
66
Hunter 44 Changes
Thanks for all the suggestions and recommendations. Perhaps I will give this Shur-pump a look. I thought about the pressure switch, too. In answer to a few of the questions, all three tanks are full. There remains solid water pressure and yes, it is pumping water nicely. It just won't shut off when the faucet is turned off and is louder than usual. When I shut off the breaker, it turns off, but as soon as I turn the breaker back on, the pump immediately activates even though the faucet is closed. I'm guessing a switch is stuck or the pump is simply bad. It is the main fresh water pump.
 
Dec 25, 2000
5,703
Hunter Passage 42 Shelter Bay, WA
Check valve on our pump was leaking a few years ago, so ordered a new pump and a replacement check valve. Repaired the old pump (now a spare) and replaced with new. Very pleased with its performance. that was four years ago. No more pump cycling and suitable for our boat. Very quiet and easy to install. Same as old one.

 
Oct 29, 2016
1,915
Hunter 41 DS Port Huron
With faucets closed and the pump running are you seeing any flow from the pumps inlet strainer? Just wondering if there is a leak somewhere in the distribution block or distribution tubing.
 
May 18, 2017
66
Hunter 44 Changes
Not sure. It became an issue just as I was heading out of town so didn't have much time to trouble shoot. Thanks for the suggestion.
 
Dec 2, 2003
751
Hunter 260 winnipeg, Manitoba
You might have a small leak between the tank and the pump. Allows a bit of air in, pressure out and causes pump to rapidly cycle or fail to shut off. I had this issue with a push on pipe fitting. Once reseated all was good. being on the suction side it never showed any water indicating the source of the problem.
 

SG

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Feb 11, 2017
1,670
J/Boat J/160 Annapolis
Big Red,
The suggestions above are fine, but before you through the pump away, why don't you systematically go through a diagnosis.

  • First, did you drain down the tank and then this problem appeared? Or did it happen "out of the blue"? (Slightly different approach to diagnosis.)
  • If you have water pressure in both the hot and cold water outlets, and no "spurts" of air pockets being purged..
  • The Jabsco pump you listed comes with quick disconnect fittings. On the discharge side, take the fitting off and replace it with a "cap" that has blocks the flow. (If you need to use a short piece of hose with a plug, do so.
  • The pressure switch should go off because the water can't go anywhere. If that's the case, the issue isn't the pump (in all likelihood). You can check this my releasing the pressure, then closing the system again. It should stop.
After that, you can check for bubbles or air pockets in the lines, or a significant leak that would stop the pump from getting to pressure. Why don't we go "step by step"? (IF you have a issue which downstream of pump, then replacing it will get you no closer to solving this issue. (I like the Shurflo pumps too, but that's not relevant to diagnosis and cure.)
 
May 18, 2017
66
Hunter 44 Changes
Excellent suggestions....

It happened 'out of the blue'.....when it first occurred, the tank was 1/2 full. I did take the time to switch it to a second fresh water tank (level full) and exact same issue.
 

SG

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Feb 11, 2017
1,670
J/Boat J/160 Annapolis
If you have "normal pressure" and flow at the outlets, then , barring some leak, I'm with the pressure switch . If you don't have pressure and flow, then it could be a bad diaphragm, low voltage.


If the outlets are closed, the pump has been running, then turn off the pump's power. You should, after a few minutes be able to open a Fawcett's and still get immediate pressure IF YOU HAVE A PRESSURE ACCUMULATOR.