My 2005 Marlin's is supplied by the fresh water tank. Last year I heard my water pump prime every few minutes or so indicating a leak in the system. The line connecting to the windshield washer was the culprit.
I was on-board until this reply....I never run with the fresh water pump on (and only use the w/w when I am running)....perhaps there is some residual pressure in the fresh water system, but I find that hard to believe....whatever...., it seems to work so far!
Hinmo, I'll try to explain how it works on our boat.
If I fill the fresh water tank, leave the pump off and open the windshield water valve, nothing comes out.
If I fill the fresh water tank, turn the pump on for a minute then turn the pump off, a little water will come out when I open the windshield water valve, then it will stop flowing.
If I fill the fresh water tank, turn on the pump and leave it on (will cycle when the pressure builds), water comes out non-stop when I open the windshield water valve.
For years I considered adding an expansion tank to the potable water system. Some of the benefits are the pump would cycle less often, you could run the water longer when the pump is turned off, etc. Is there any chance that your boat has been fitted with an expansion tank?