water pump won't shut off

[Jimongee]

I need some help regarding my water demand pump. I am a pretty technical guy and I have owned several RV's with demand pumps operating the water systems. However, this is my 2nd day of ownership for my 2002 356 Hunter. The boat has been well maintained and is in pristine condition. However, the demand pump will not shut off unless I shut it off. I have assured the fresh water tank is full, all devices are connected and no leaks present. When I cycle it on there is great constant water pressure from any tap but when the tap is shut off-the pump will run on indefinitely. I did confirm all air is purged out of the system and the hot water tank is full. I am stumped. Before I disassemble the pump can anyone provide some tips?
thanks,
jim and kathy in Port Sanilac, MI

 

[Stu Jackson]

Assuming you mean "I have assured..." rather than "I have BEEN assured..." then it's gotta be the pump pressure diaphragm. Some can be repaired, some need replacement or a new pump. General consensus has been if it's an older pump it may make sense to get a new one with variable flow.

 

[Bill Roosa]

Agree with Stu, the pressure switch has to be the trouble maker. One other thing to check before you commit though. Does you boat have a fresh water shower at the stern? Had the situation where I recommissioned the boat and forgot to turn off the shower faucets. With the leak going overboard and not into the boat it took me some time to figure it out. Luckily the first mate has a good eye for details.

 

[kloudie1]

One tiny piece of debris in a discharge valve (thinking a three chamber pump like the Shurflo) can not let the pump build pressure but still let it flow a good bit at the tap.. Pressure switch is the most likely.. but if a new one (micro switch available at Radio Shack or equivalent) and cleaning the pressure switch piston does not cure the running, then Take the pressure head off and clean it and the 6 check valves up.

 

[John23883]

Crud in the faucet

I get crud, plastic bits from the tank, etc. that get between the faucet handle rubber gasket and the brass base of the faucet. That's all it takes and the pump wonn't shut off. I shut off the pump power, pull the faucet handle and clean the crud out and it stops.

 

[Jimongee]

Thanks Everybody,
Sorry it has taken me so long to respond with my problem solving on this run on water pump. I found it had an air lock [cushion of air] at the furthermost end of the system v[the cockpit shower faucet]. Once I had purged the air the pump pressurized and problem solved!
thanks for all your help.
jim in Charlevoix, MI-Hunter 356

 

[onecoolair]

Yup..the pressure head switch on pumb best guess. On my 356 it is plumbed with pex plumping there is a distubution panel under the galley sink. One of the cut off valves stuck open and broke off. It was for the cockpit shower which malfuntioned and blew seal one night. Empting Tank. Cut pex and installed a new in line cut off valve under sink. It stays off unless we are going to use cockpit shower. Then at water heater it did the same thing on another night. I install another cut off valve right before waterheater. Now when waterheater springs a leak again I can just shut it off, and fix it later but still have pressure to galley and head. Also added switch to pump which is just inside cabinet door under sink. Now I can turn power to pump on and off only as needed.