Water Pump - Help

[jeddlad]

The (fresh) water pump is coming on every 1 minute and 20 seconds (or so) but only for 2-3 seconds each time. I haven't noticed a leak but not all the pipe work is easily accessible. I'm not noticing a drop in the water level in the tank but haven't been monitoring for long.

 

Could this be the diaphragm or does it sound like a leak?

 

The water pump is a Jabsco flow Jet PR 405 - 143

Edited August 5, 2012 by jeddlad

[RLWP]

To eliminate the possibility of a leak, look in the cabin bilge at the back of the boat

 

Richard

[jeddlad]

The bilge at the stern of the boat is bone dry (it's just been re-painted - Great job - Thanks Ian.)but I don't see any other access into the bilge apart from the engine compartment.

 

I did think that the engine compartment was sealed from the main bilge??

[RLWP]

The bilge at the stern of the boat is bone dry (it's just been re-painted - Great job - Thanks Ian.)but I don't see any other access into the bilge apart from the engine compartment.

 

I did think that the engine compartment was sealed from the main bilge??

 

That's correct on a modern boat

 

So, the cabin bilge is dry, but your pump still cuts in. Have you got a dripping tap or shower?

 

Richard

[Grace and Favour]

The bilge at the stern of the boat is bone dry (it's just been re-painted - Great job - Thanks Ian.)but I don't see any other access into the bilge apart from the engine compartment.

 

I did think that the engine compartment was sealed from the main bilge??

 

Cabin bilge - not engine bilge..........

[blackrose]

If you're sure it's not a leak then (assuming you have a calorifier), try turning the pressure relief valve open. It's on top (or at one end of the calorifier) and is spring loaded so it will shut by itself. It could be that a build up of limescale is causing it to leak and turning it open a few times may dislodge the crud so it can seal.

 

Also try checking under the pump for a wet floor (some pumps leak). The only other thing I can think of is that the non-return valve in the pump is leaking and water from the pressurised (downstream) side of the pump is leaking back upstream to the non-pressurised side of the pump. Once the pressure reduces then the pump will activate to build pressure up again, and so on.

Edited August 5, 2012 by blackrose

[jeddlad]

The engine compartment is bone dry but I can't see any access into the cabin bilge at all. The carpet has always been a bit damp to touch near the side hatch but we thought this would clear up after the side hatch was re-sealed etc.

 

Thanks for the suggestions, will go to the boat tomorrow and will report back

[blackrose]

Well, while you're away switch off the water pump!

[jeddlad]

LOL - Yes I did that

[JamesWoolcock]

Had same problem last year and it was a duff accumulator

 

James

[Rebotco]

Me too. Turned out to be a small leaky fault on the bog flusher valve. I expect there is a more technical name for it, but its late and I can't remember!

It was dripping into the bowl, so not easily visible. Quite easily fixed though.

[nicknorman]

If the pressure has fallen enough to start the pump, but it only takes 2 or 3 seconds to reach cut-out pressure, that suggests an inadequate accumulator function. I suggest you check the accumulator air pressure. With water pump off and a tap open, put a car tyre pressure gauge on the air valve (typically on the top of the accumulator). It should be slightly below pump cut-in pressure, say around 15 to 20psi. If low it needs pumping up with a foot pump. It may have developed an air leak.

 

With the rate of leaking you are talking about, but with a dry bilge and no leaky taps / loo,PRV not leaking, next most likely cause is a leaky non-return valve within the pump itself, which is allowing high pressure water to leak back into the tank. You could try letting the pump run, then as soon as it stops, turning off the stopcock at the tank outlet. This would prevent any flow back into the tank. However if the pump does cut in again after the usual time, be sure to open the stopcock pronto to prevent the pump from running dry.

Edited August 6, 2012 by nicknorman

[jeddlad]

Thanks for all your ideas / suggestions.

 

Turned out to be an easy fix - air lock in the water system. Filled the tank continuosly with the hose, had the taps and shower on full blast until the airlock was gone.

 

Thanks again