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Old 23-10-2021, 10:18   #1
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Fresh Water Pump Running Constantly

The fresh water system on our two-year old boat has a Jabsco Par-Max 2.9 pump. It's worked fine so far, then just recently it began running constantly, unless I turn off power from the DC panel. The water tank">fresh water tank is full and the pump is delivering plenty of water pressure to the faucets. Only, when the faucets are all shut off, it doesn't stop running, as if the system wasn't pressurized. I checked for leaks and blockages up and downstream and there are none. I assume it's the pump that's malfunctioning. A Jabsco video shows how to clean the check valves to solve a non-priming problem. Could that also cause the above symptoms?

Any suggestions to troubleshoot this problem would be appreciated!
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Old 23-10-2021, 10:37   #2
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Re: Fresh Water Pump Running Constantly

Did you run out of water and refill recently? If so you have air in the system somewhere. The air doesn't allow the pressure switch to operate properly. (it's too "soft" like a cushion in the pressure.
Otherwise you may have a defective pressure switch on the pump.
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Old 23-10-2021, 22:22   #3
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Re: Fresh Water Pump Running Constantly

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Originally Posted by Cheechako View Post
Did you run out of water and refill recently? If so you have air in the system somewhere. The air doesn't allow the pressure switch to operate properly. (it's too "soft" like a cushion in the pressure.
Otherwise you may have a defective pressure switch on the pump.
Certainly a possibility, but since there's good water flow, wouldn't the air work its way through the system and spurt out through the faucets?

If not, how do you purge air from the fresh water system?
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Old 24-10-2021, 04:36   #4
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Re: Fresh Water Pump Running Constantly

From the Jabsco Manual’s ‘Troubleshooting’ guide ➥ http://www.tcschandlery.co.uk/files/pdf/pdf5899.pdf

“Pump fails to turn off after all fixtures are closed”
Empty water tank
Punctured pump diaphragm
Discharge line leak
Defective pressure switch
Insufficient voltage to pump
Debris under flapper valves
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Old 24-10-2021, 05:00   #5
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Re: Fresh Water Pump Running Constantly

For $100 buy another and stick it in. Process of elimination.
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Old 24-10-2021, 05:29   #6
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Re: Fresh Water Pump Running Constantly

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For $100 buy another and stick it in. Process of elimination.
Yes.
Or unhook the output side of the pump from the rest of the boat and hook it to a short piece of tubing with a valve on the other end. Run the pump with that open valve into a pail of water until there are no air bubbles. Close valve and see if pump stops. If pump stops the problem is most likely downstream. If it does not stop the problem is likely pump-based or towards the water tank.

Does the boat have a hot water heater and/or a winterizing loop for introducing RV antifreeze to the system? Dock water port? Pressure tank? More valves and connections to check...
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Old 24-10-2021, 05:56   #7
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Re: Fresh Water Pump Running Constantly

From the checks that you have already run a leak downstream and air in that system do not sound likely. When you have air in the system the pump runs after you close the faucet but then stops as the air is pressurized, and yes, it bleeds out. A leak downstream would leave you with a lot of water wandering about the boat and an empty tank.

In a simple sytem that pretty well leaves the pump letting pressurized water back to the non-pressurized side. It can do that with a stop valve that isn't sealing and with a perforated diaphram. Both are repairable, but substituting a new pump, as Telepare suggests, is quick and easy - the Par-Max pumps have simple bayonet water connections leaving just the two crimp connectors. If that solves the problem, then you can order the part(s) and make the repair at your leisure. A spare water pump is well worth carrying.

Good luck with it.
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Old 24-10-2021, 06:27   #8
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Re: Fresh Water Pump Running Constantly

When you turn all of the faucets off, do you hear the pump load up and slow down? If so, it's either a small leak, or the pressure switch isn't shutting the pump off. If it's not loading up, there's either a big leak, or air somewhere that's preventing it from building pressure.
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Old 24-10-2021, 08:29   #9
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Re: Fresh Water Pump Running Constantly

Check valves would be where I would be looking.
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Old 24-10-2021, 08:40   #10
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Re: Fresh Water Pump Running Constantly

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Certainly a possibility, but since there's good water flow, wouldn't the air work its way through the system and spurt out through the faucets?

If not, how do you purge air from the fresh water system?
Sometimes it will not just get pushed out.. Especially if there is a loop UP in the tubing. Water flows through it, but it is still in that UP loop. It probably wold with more flow but these pumps dont really flow a bunch of water.
I had one boat that would do it every time if I let it run out of water. Needless to say I was careful to not be lazy and let that happen eventually.

It may come out with continued running of water from the highest faucet in the boat, although you should do all of them.
Do you have a stern shower? That's another culprit for accumulated air.
Otherwise see if you can find a significant UP loop somewhere, and disconnect to get it out or lower it down to allow air to flow further on etc.
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Old 24-10-2021, 08:58   #11
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Re: Fresh Water Pump Running Constantly

Odds are high that you have a faulty check valve in the input to the pump. Water is leaking back to the tank when the pump shuts off causing a loss of pressure which turns the pump back on. If the check valve is leaking a lot of water back into the tank, the pump will run continuously trying to keep pressure in the system. I'd start by taking the pump apart and looking for some trash on the check valve diaphragm(s).
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Old 24-10-2021, 09:18   #12
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Re: Fresh Water Pump Running Constantly

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Originally Posted by Spot View Post
Yes.
Or unhook the output side of the pump from the rest of the boat and hook it to a short piece of tubing with a valve on the other end. Run the pump with that open valve into a pail of water until there are no air bubbles. Close valve and see if pump stops. If pump stops the problem is most likely downstream. If it does not stop the problem is likely pump-based or towards the water tank.

Does the boat have a hot water heater and/or a winterizing loop for introducing RV antifreeze to the system? Dock water port? Pressure tank? More valves and connections to check...
+1 on this. We installed a "Y" valve at the output of our pump for bleeding with the bleeding port having a hose to the bilge. Helps when cleaning the bilge as well. I simply cannot bleed my system without this.

Bleeding can be a pain requiring multiple attempts. Assuming you've bled the system well by running all taps and all look fine without air, next step in my opinion is to replace the pressure switch.

If you have an accumulator tank and it has a hole in the bladder or the air pressure doesn't match the pressure switch, that could cause the pump to run continuously as well.

Check the air pressure in the accumulator tank and match the specs for the pump, and keep the pressure tester on the accumulator tank while running water from a faucet until the pressure drops, then turn off the faucet and you should see the pump causing the air pressure in the accumulator tank to rise, then cut off at the set point (typically 20-40 psi). This test only works if the pressure switch is working, so replace that first as above.


Oh, and don't forget to check the entire system for leaks and tighten all clamps. You'll be surprised how many clamps will loosen over time with vibration and temp changes. This should be an annual maintenance item for all of us- all clamps on a boat should be inspected and tightened annually or so. I've found many that somehow rusted and cracked since the last time I checked and I think I've averted many potential disasters over the years by doing this.
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Old 24-10-2021, 10:11   #13
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Re: Fresh Water Pump Running Constantly

Had the same issue, same symptoms. Turned out to be the pressure switch, which wasn’t serviceable.
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Old 24-10-2021, 11:00   #14
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Re: Fresh Water Pump Running Constantly

Thanks for the many suggestions and shared experiences. A new pump (with automatic pressure switch) was ordered. Will see if that solves it as theres no evidence of any of the other root causes, or I don’t have the right tools to test for them them. To be continued.
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Old 24-10-2021, 13:05   #15
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Re: Fresh Water Pump Running Constantly

Quote:
Originally Posted by Howler View Post
The fresh water system on our two-year old boat has a Jabsco Par-Max 2.9 pump. It's worked fine so far, then just recently it began running constantly, unless I turn off power from the DC panel. The fresh water tank is full and the pump is delivering plenty of water pressure to the faucets. Only, when the faucets are all shut off, it doesn't stop running, as if the system wasn't pressurized. I checked for leaks and blockages up and downstream and there are none. I assume it's the pump that's malfunctioning. A Jabsco video shows how to clean the check valves to solve a non-priming problem. Could that also cause the above symptoms?

Any suggestions to troubleshoot this problem would be appreciated!
Pump that runs constantly is because the pressure switch does not read the pressure in the pressure tank. Two causes, one the small pressure line tube from the pressure tank to the bottom of the switch is blocked, This is common as the line is very small, To repair or check, shut the power off and drain the system, Remove the line off and check the ends, You might need a small wire to clean the ends and also check the inlet to the tank and the switch. Now that the line is reinstalled check the tank air pressure as this is your reserve pressure before the cycling of the system. It should read 18 to 22 lbs pressure (if my memory serves me correct) check you instruction manual. If your pressure tank does not hold pressure, your bladder is punctured or ripped and the tank needs to be replaced. If the bladder is OK. Restart the system. If the pump does keep running, the pressure switch is defective.
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