Flojet fresh water pump

Leighb

Leighb

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I have a Flojet 4405 water pump.

It was working fine, but now cycles every few secs when taps are closed. It still pumps effectively. There are no leaks evident.

If I listen closely I can hear what sounds like a suction hiss between the bursts of pumping noise.

I have opened up the pump and there is no obvious split in the diaphragm or sign of anything stuck under the valves. Cleaning it all up has made no difference.

What next? Do I need special tools to dismantle further?
Are service parts available for this pump?
 
have you got an accumulator in the system ? That might explain an "air" hiss, but a "water" hiss can only be a split pipe or leaking union / diaphragm under pressure.

Is there any unexplained / unusual water in the bilge ?
 
I have a similar pump which provides galley salt water (no accumulator) and exhibits the same behaviour. I have been unable to fix it and assume that it is 'back leaking' into the supply line, and so that is tripping it into repressurising every now and again. Fortunately we don't use galley salt water often so we keep it off. FWIW I recently changed the fresh water pump for the new electronic sensor type which meant I could ditch the accumulator. It runs much more quietly (variable speed) and may be an option to look at if you decided to dump the pump.
 
If there really are no leaks then it is almost certainly the pump valves at fault.

If you select you pump on this web page you should then be able to access a spares list. There will probably be a valve overhaul kit listed.
 
No accumulator, no unusual water in bilge. I have double checked all unions to ensure they are as tight as poss.

I guess it must be valves and will check out the site for spares
 
[ QUOTE ]
You could try fitting a non return valve to the pump discharge

[/ QUOTE ] Won't help with the pressure switch integral with pump but one in the pump suction might!
 
Got to be the pressure switch. Its the little black squarish box at end of pump.There,s a micro switch inside,that could be faulty.You should be able to get a spare .
 
[ QUOTE ]
Got to be the pressure switch

[/ QUOTE ] If it switches on and switches off I disagree.
 
I don't disagree at all. It could be the pressure switch, the pressure switch diaphragm or even a blockage in the internel bypass in the pressure switch - it may even be a blockage in the valves..

Unfortunatly you either have a small airleak somewhere in either the pump or the system or the supply voltage to the pump is low - have you checked the quality of the electrical connectionns???

1, Check the voltage at the pump when the pump is running
2, Service the pump completely...
3, Smile and buy me a pint.....
 
[ QUOTE ]
the supply voltage to the pump is low

[/ QUOTE ] If it switches on and pumps normally on demand please explain to me how a low supply voltage or poor connections could make it cycle every few seconds when the taps are off.
 
I have fitted the valve kit, but unfortunately not cured the problem, so have now ordered the diaphragm kit, will keep you posted /forums/images/graemlins/frown.gif
 
That's annoying
Do make absolutely sure you don't have a leak anywhere on the system. It will only take a tiny leak or a tap dripping to cause the problem.
 
Thanks, yes I tried checking for leaks at the start, much of the pipework is new, and I have looked at all joints, tap connections etc. No sign of any leaks, also I can hear this hiss between the bursts of pumping which is definitely coming from the pump itself, so it would appear that there is an air leak in the pump somewhere.

Or I suppose it could be water leaking back onto the inlet side? I would think that new valves would have fixed that possibility though?
 
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