Grrrzzzzz

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Jun 7, 2007
515
Hunter 320 Williamsburg
The pump for my freshwater tank won't shut off automatically. Have checked for air leaks, and yes the tank is full. Any ideas? Thanks.
 
Jan 22, 2008
1,668
Hunter 34 Alameda CA
If it had been empty, it needs to purge out the air from the lines. Open all the faucets individually and make sure they are burped. Hopefully then it will cycle and stop pumping.
 
Nov 6, 2006
10,113
Hunter 34 Mandeville Louisiana
If it is making pressure and doing that, the pressure switch is inoperative.. could be a bad switch or the little piston that actuates the switch could be bad.. This would make it run slowly and struggle when all the water is turned off.. If it is not making pressure, the problem could be a plugged strainer or crimped pickup tube or some other restriction on the suction side, including air leaks.. or it could be a bad valve or rather trash in the valve or valves.. or is it pumping water into the bilge from a leak in the line? Model/Type?? Pictures?
 
Jun 6, 2006
6,990
currently boatless wishing Harrington Harbor North, MD
Could be sucking air

If there is an air leak in the intake it can run forever as the valves don't seal air that well. Mine will suck air through the strainer quick disconnect every time I purge the system and mess with it.
 
Dec 2, 1997
8,967
- - LIttle Rock
If it's a diaphragm pump...

Most likely the diaphragm has failed/worn out. The diaphragm is a thin rubber membrane that wears out over time...first a tiny hole that gets larger. So what you have is an air leak in the pump that's causing the pressure to drop, which causes the pump to run to try to restore it.

The first sign that's happening is a pump that starts cycling for no reason...at first just the briefest little "brrp" every few hours...then a little longer and more often...till finally the pump runs continuously but won't pump any water.

You can buy diaphragm kits, but pumps aren't that expensive...so if the pump is more than about 10 years old you're better off just replacing the pump. 2.8 gpm is the right size for any boat 25-40'.
 
Oct 14, 2005
2,191
1983 Hunter H34 North East, MD
What Claude and Peggy said...

are all probabilities. When my pressure switch began failing it acted just as Peggy described for the diaphram failure. See if there is an adjustment screw head on the little square box where the wires come out. Adjusting it could solve your problem temporarily, but start looking for a new pump if it does as it won't be long before it doesn't work at all!
 
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