Flapper goes off for no reason

Oct 14, 2020
28
Beneteau 343 Burnt Store
My flapper keeps going off every 20 seconds. My bilge is bone dry. Its is a consistent pulse. I have checked the wires - all seems ok. I even changed the circuit breaker. Any ideas? The bilge breaker is on the off position. So only water in the bilge should set off the flapper; it seems like it is getting an electrical "hit" to go off..
 
Jun 21, 2004
2,532
Beneteau 343 Slidell, LA
So are you referring to the bilge pump float switch? If it is indeed the bilge pump that is activating, perhaps the float switch is shorting out.
Sure it isn't the pump for the fresh water system that is going off. If so, you may be able to adjust the pressure switch in the pump. If that doesn't solve the problem, time to rebuild the pump or replace it. I recently replaced my pump after 15 years of service.
 
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Oct 14, 2020
28
Beneteau 343 Burnt Store
Yes, I meant the bilge pump float switch. (Sorry.. wrote late at night)... we did check for a short where it connects to the pump.. all seems ok.. It is silent this morning.. but that doesn't mean it will act up again.. I will check the fresh water pressure switch... do you rebuild the bilge pump? Also, last night all "heck' broke out in the aft cabin - lots of load sucking and gurgling noise... but all seems dry...

My Yammar is in perfect shape.. a recent (Big) overall with al very competent diesel mechanic... so I can't see a lieak or even a semll coming out of there

As for my Float switch.. it has now started up... put only a pulse every 3 or 4 minutes.. it increases during the day.. and evening.. Now.. I am wondering if it is (instead) my FRESH water pump... just used my sink.. and it is now starting and after I clean up at night (more fresh water)... it goes off alot... I think I will head down that trail... I am not much of a mechanic... would you just replace the whole fresh water pump system including pressure switch??
 
Oct 22, 2014
20,995
CAL 35 Cruiser #21 moored EVERETT WA
It sounds like you are new to boating and new to this boat. The statement "last night all "heck' broke out in the aft cabin" I am assuming did not involve persons or animals cavorting.

With those assumptions, my first recommendation is to start at either the bow (front) or stern (back) of the boat and open every cupboard, door, and hatch taking pictures and exploring everything inside all of the voids so you know what is there. If it is something mechanical, turn it on and watch it operate. If it fails to work as you expect take pictures and make note of what you see, hear and smell. Once you have all of this new information start to categorize it as to what it does, how it worked, and why it is on the boat.

Only by knowing what is there and how it works can you possibly be able to understand what is happening to your boat when you hear a strange sound or smell a bad smell.

Once when sleeping on my boat there was a tremendous ruckus going on. I thought it might be in the V-berth. No it was on the bow above the V-berth. To ducks were cavorting leaving their feathers and a mess on the bow when I leaped out of the cabin with my flashlight.

Duck Coitus Interruptus.
 
Jun 21, 2004
2,532
Beneteau 343 Slidell, LA
Swisssally,
I did replace the diaphragm impeller on my "Whale" bilge pump several years ago at a reasonable cost. Very simple repair.

With regards to the Shurflo fresh water pump, there are two separated impellers inside the pump and I was not sure which component was problematic. The pressure switch is an internal part of the pump. Purchasing the two components would be about 2/3 the cost of a new pump. After ruling out leaks, air in system, and obstructions, I replaced the 15 year old pump with a new one.
The comparable model that I selected was a Schurflo Blaster II washdown pump (12 VDc, 3.5 Gpm) at a cost of $135 including shipping.
Simple replacement as the fittings for the original Schurflo pump were the same as the new one. The old pump model was no longer available. I am sure that you aware of this, the freshwater pump is on the port side behind the setee cushion in the salon. Might want to check the filter/screen upstream from the pump to make sure it isn't obstructed.
 
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Mar 20, 2016
594
Beneteau 351 WYC Whitby
I keep my fresh water pump off ,only turn it on when going to use water and then shut it off ,made it a habit . If a line lets go ,you will empty the tanks into the boat
 
May 17, 2004
5,032
Beneteau Oceanis 37 Havre de Grace
As for my Float switch.. it has now started up... put only a pulse every 3 or 4 minutes.. it increases during the day.. and evening.. Now.. I am wondering if it is (instead) my FRESH water pump... just used my sink.. and it is now starting and after I clean up at night (more fresh water)... it goes off alot... I think I will head down that trail... I am not much of a mechanic... would you just replace the whole fresh water pump system including pressure switch??
I’d do more troubleshooting before replacing the pump or pressure switch. First, to see if it’s actually the pump - Does this random cycling make the same sound as what you hear when you have a faucet on? The bilge pump should be a somewhat different type of noise than the fresh water pump. Also, when you hear the random cycling, does it stop if you turn off the fresh water breaker?

If you do ensure that the noise is the fresh water pump cycling randomly then I’d still check for possible leaks before assuming the pump is bad. You could turn off the fresh water breaker and wait some time, then turn on a faucet and see if there’s still pressure.