Fresh Water Pump Bad ?

K

ken emigh

Member
Joined
Mar 25, 2007
RO Number
25623
Messages
154
Filled fresh water tank opened faucets and turned on pump. It ran and ran and ran but no water was flowing. Closed faucets restarted pump. It ran and ran and ran. Open faucets still no water flowing. Shut system down pulled out 20 year old pump. Went to West Marine picked up new one. It goes in this Sunday. I didn't do anything different as in previous years and followed the Carver Manual.
Am I on the right track with this?
 
Sometimes sediment, etc, in the tank will seal off the water supply to the pump, and nothing will come out when it runs. However, considering that you say the pump is 20 years old, the pump is likely the culprit.
 
The old unit is a shurflo 2.8, new unit is shurflo 3.0. Will this make a difference? Also don't know why but on the old unit on the outlet side there is an inline check valve? I don't see in any of the diagrams that it calls for a check valve. Any ideas what they were trying to do? Note their is no accumulator or strainer that I know of and did not see any.
 
Is it a diaphram pump? My dad had a couple boats that the pump had to be primed before it would pump water. If air got between the pump and the tank he would have to get that out before it would pump water.

The check valve on the outlet side is there so water cannot be forced back through the pump. When we first hooked up to dock water I did not have a check valve and I almost blew a water tank up because the water preasure was great enough to go back through the pump and fill the water tank.
 
My shurflo sometimes does not prime after the tanks have been empty even though it is gravity feed from the tank. I remove the intake hose from the pump and let all the air out. Put the hose back on and it works fine.

The check valve on the pump discharge is there to keep dockside water (if equipped) from back flowing through the pump and filling (or over filling) your tank.

Also, for future reference, if you have a farm supply store (i.e. Rural King) close by you may want to check there for 12 volt shurflo pumps. I bought my 2.8 gpm pump there for ~$40. Farmers won't pay what boaters will :)
 
Mine will do that if the screen filter gets clogged, once I clean the pump's filter it works.
 
a check valve on the inlet side helps keeping it primed... not a must have but nice if you have a long / high hose run. check the screen on the inlet side. Most pumps are rebuildable by just replacing the diaphragm. Also, if you dont' have any screen, you can have "stuff" stuck in check valves in the diaph. worth opening.
 
A check valve on the outlet side will protect the pump from backpressure when you are connected to shore water. However it might also help to trap air in the pump. I'd disconnect the discharge line right at the pump and see if it can pick up it's prime.
 
New pump did the trick. However now I have a cycling problem. So I'm chasing down leaks, found one so far.
 
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