[C320-list] water pump won't shut up

[Gary Magnuson]

Good morning Nat,
As I understand our systems, the water pump is a pressure demand pump 
that starts when it recognizes a drop in system pressure by opening the 
faucet valve. If the tank is dry, then the pump cannot pull water into 
the piping to bring the pressure back to the cutoff point.  Since you 
had to pull the wire off the back of the panel pump switch, it is 
possible you have a bad switch.  To test the panel switch, use a meter 
or a test lamp across the contacts in both the open and closed position 
and see if you have continuity.  You should read a short when the switch 
is on and an open when the switch is off.   If the readings are the 
same, the switch is bad. But you should be able to still operate the 
system if the pump pressure switch is still working.  In order to test 
that, I would fill the tank so that the pump has the water it needs to 
pressurize the system.  (verify that the pump strainer is clean,  I 
found mine to be fouled with plastic shavings and other stuff in the 
past. When it is clogged, it will not allow the pump to prime and build 
the pressure it needs to satisfy the pressure switch.  With the tank 
filled and strainer clean, start the pump again and see if it will prime 
and come back up to pressure.   With the tank filled, it should 
re-pressurize and shut off when the water pressure rebuilds. The sink 
faucet valve just is the way we drop the pressure to start the pump and 
stop the water flow in order for the pump to rebuild the pressure 
necessary to activate the pressure switch.

Sorry for the long winded answer.  I hope it made sense...
Good luck,
Gary Magnuson,
#205   Time A Weigh
On 7/21/2012 11:33 AM, Nat Antler wrote:
> My automatic water pump wouldn't shut off when the sink faucet was closed. It happened when the water stopped flowing so I assume the tank was empty. No matter what I did with the faucet valve the pump kept going and the toggle switch on the panel had no affect so I had to open the panel and pull the power wire from the back of the switch. Questions: is the switch bad? does this happened when the tank runs dry? Is the pump bad? Is the control on the pump that activates it when the water is turned on bad?
>
> Would be most grateful for insights before I start replacing things that may or may not fix the problem. Thanks, Nat Antler 1994-5 320 #161