Water Pump Won’t Stop Pumping

[Alec H]

It’s sucking air from someplace, but that’s the riddle. Backstory - I replaced the heating element and thermostat on the water heater. From that point on, the pump took longer to cycle on and then off. That is, I could use more water before the pump would kick in, and it took longer for the pump to pressurize the system. It was as though I had installed a bigger accumulator. I was wondering if the water heater had started to function like an accumulator.

Coincidently, I discovered a leak in the aft water tank. The location of the leak is still unknown, but when I fill the tanks, I find water in a compartment next to the aft tank; a compartment near the batteries and the selector switches. Once the tank is down to ¾ full, the leaking stops. Yesterday I filled this tank, it seemed to take too long to fill; and sure enough, I found about five gallons in the main bilge, but no water from the vent.

Recently, the water pump has been cycling on, sucking air, when both tanks still read ¼-½ full; just as it normally did when a tank runs dry and you switch to the other. Sometimes, after a few minutes, it will pressurize, but usually I shut it off, fearing it will burn out from running dry.

I can deal with the leak by simply not filling the tank all the way, but the cycling pump is another matter. Where is the air coming from? Any suggestions on how to solve the pump problem without removing the tank?

[Stu Jackson]

Every single domestic water pump comes with a very helpful TROUBLESHOOTING guide in the manuals, all of which are AVAILABLE ONLINE. Regardless of which "standard: pump you havem all the vendors are pretty much the same, although I've found Shurlfo or Johnson to be superior to Jabsco, same stuff better materials.


Every time someone asks this recurring question, I guide them to the, uhm, guide. It is there for a reason. There is simply no one on the internet who is going to find your leak except YOU.


I had this issue, did the pump diagnostics, then found the leak in the at that time 28 year old hoses.


YOU simply have to go find it.


Good luck, it's time consuming, but patience will out.


Sometimes lotsa patience, but still...