Why won't my water pump stop if there's no leak ?

[Brann-]

Hello,

I've installed a water pump (Jabsco PAR MAX 2.9), which is connected to two filters (5mic and a coal filter), and then directly to the tap.

I thought this setup was foolproof, but apparently it's not. When I first started the pump with the faucet open, it pumped water through the filters and to the tap without problems, but once I closed the tap, the pump never stopped (I manually stopped it after 5 minutes). I've checked for leaks by following all the piping, and there's none. Should I let the pump on longer before it stops ? I thought it would stop almost immediately since there's no pressure tank in the system (and start immediately as soon as I started using water).

The other weird thing I witness is that the water flow is very irregular. Do all pumps produce that kind of irregular flow, or is it only this specific model ? if so, I guess I will have to install a pressure tank after all ...

Thanks a lot!
Brann

[ranger58sb]

New pump? Maybe just some debris affecting the switch...

Or... is there sufficient supply from your freshwater tank?

When bleeding air, it's sometimes useful to open all the taps at once...

Otherwise, hidden leak, somewhere you can't easily see?

Our PAR MAX isn't a continuous duty pump, so it's intended to be used with an accumulator. Even with that, flow rate surges and ebbs a little. We haven't found that to be a problem...

-Chris

[Brann-]

This is indeed a brand new pump. I have no idea how the switching mechanism works ; I guess there's a pressure sensor which cuts the operation when the pressure is above a certain level ?

There is enough water in the tank, and I'm positive there's no link (the pump is below the sink, so there's only a couple of very short pipes).

I'll look into plugin in an accumulator somewhere !
Cheers,
Brann

[msponer]

I've had several of that style of pump, and they will run continuously if:

• One of the diaphragms is torn (allowing pressurized water to leak back into the unpressurized side)
• If not assembled properly -- the screws that clamp the silicone diaphragm between the two plastic pieces have to be uniformly tight
• The DC pressure switches tend to not like running without an accumulator. Because the 'sweet spot' between on and off is small, so the cycle rapidly without moving the switch that much. This causes them to eventually fail on or off. This can be fixed by taking it apart to manually flick the switch several times.

So, I think you may just want to return it and exchange it for a new one. Or, if it's too late, take it apart to check the membrane and switch.

As a side note, I'm really not impressed with the quality of this style of pump. We standardized on the whale ones (our boat has 6 pressure water pumps of various kinds), and we've had to replace 4.

[Brann-]

Ok, i'll open it and see what I find inside ! I didn't know those pumps wanted an accumulator to run properly !

[Stu Jackson]

RTFM

Really, they all have very good troubleshooting guides in them.

Also check that the screen in your faucet is clear.

[sck5]

also check that there is no blockage on the supply side. Sometimes the pickup in the tank can get clogged. You should be able to disconnect the supply line at the pump and be able to blow bubbles into the tank without too much effort

[HopCar]

When a pump like that won't shut off and there are no obvious leaks, I look at the valves inside the pump. They do wear out with age or something can get in and hold them open. It never builds enough pressure to activate the switch.

Of course the switch could be bad.

[DeepFrz]

If it is crap in the valves then you need to do two things. 1: clean your tank. 2: install a water filter between the tank and the pump.

[Brann-]

Originally Posted by Stu Jackson

RTFM

Really, they all have very good troubleshooting guides in them.

Also check that the screen in your faucet is clear.

Reading the manual was the first thing I did, available here for your convenience

as you can see they don't mention anything about an accumulator... Also, I can't see how my faucet can be relevant since I have the problem when the tap is closed.

thanks for the suggestion though.
Brann

[Brann-]

The install is brand new. It's a new tank I just installed, with clean water in it, new piping, and a new pump. Granted it might be a defect in the pump itself. I might get it back to the shop...

As anyone any idea of how long it should take the pump to stop when there's no accumulator and the circuit has already been filled with water ? Since there's nothing to pressurize, I would have thought it would be almost instantaneous, right ?

Brann

[ranger58sb]

Originally Posted by Brann-

As anyone any idea of how long it should take the pump to stop when there's no accumulator and the circuit has already been filled with water ? Since there's nothing to pressurize, I would have thought it would be almost instantaneous, right ?

Yes, maybe 10-15 seconds on first go. After that, maybe 2 seconds to re-pressurize after you've started the system and then turned it off for a while.

-Chris

[Dauntlessny]

This has happened to me.
It turned out to be air getting into the supply line between the water tank and the pump.

Re-check very carefully all of your fittings. Even when I had checked once, it did not figure it out until I let the pump run and heard air being sucked.

[masonc]

All of those micro switch controlled pumps work so much better with an accumulator to buffer the water flow. Remember, water is not compressible and you water hammer the pump when you turn off the flow.
I would not think of installing one without at least a 0.6L accumulator.
Also, the micro-switches give trouble. Try removing it from the top of the pump and see if there is some gunk stopping it from activating.

[motion30]

When I had this problem I installed a short section of clear PVC hose in the suction side so I could see any air bubbles. Turns out the jabsco pumps are just junk