Water Pump will not shut off

[beachperson]

Hi,

My water pump will not shut off when I use the fresh water.

[Cypressloser]

Is this a new trailer or motor home, are the valves set correctly, is there an airlock in the system, is the tank full, is the pump trying to fill the hot water tank, what is the make and model of the pump?

[beachperson]

This is a Dynamax, Isata 3, 2017, Motorhome. It has an instaneous hot water heater. I bought a new water pump, and it is a Shurflo 4008 fresh water pump.
The valves are set correctly. The tank is full. I have opened all the faucets and ran the city water and the fresh water.

[Cypressloser]

This helps a lot, your MH is still under warranty, so you don't want to mess to much with the pump. If you are certain that all the valves are set correctly and everything has been working fine on city water then the pump settings may need to be tweeked.
We have exactly the same water pump, and it was working just fine initially but we spent 2 months on full hookups and never used the pump. Now the nights are getting colder and we had to start using our fresh water tank and ran into the same issues you are having.
The 1st thing I did was check the pressure on the whole system by connecting my pressure regulator, which has a pressure gauge on it, to the outside shower hose and the other end to the sprayer nozzle to keep the system closed and pressurized. The correct pressure should be between 40 and 45 psi, if it is higher than that it can push the back pressure bypass valve open which basically keeps the pump running in circles, this valve is a safety device to keep the seals from blowing out in case the pump pressure is to high.
On the pump head is a black cap with a small recessed 5/64 allen head screw, you can try turning this screw in to increase pressure or out to decrease but do it in small increments and have someone watch the pressure gauge and discharge small amounts of water til you have it properly adjusted. This procedure is not explained in the pump's manual, Shurflo does not want you to mess with it but it did fix it for us.

[random_james]

Originally Posted by beachperson

Hi,

My water pump will not shut off when I use the fresh water.

I ran in to this once with my Isata 5 - turned out I had left the Tank Fill valve in the open position, so the water pump was trying to pressurize the lines, which pushed water in to the water tank, which lowered the pressure, so the water pump would continue to suck water from the water tank to try and pressurize the line, and the circle would continue

Not sure if the 3 has the same valve setup as the 5, but worth a check!

[beachperson]

Thank you for all of these suggestions. I did finally get the water pump to work properly after much trial and error and patience. I adjusted the screw on the pump head and worked on the valve.

[bclemens]

FYI...there is also a back flow device that allows water back into the water tank if the pressure is too high (thus the adjustment screw on the pump). It prevents you from doing damage to the water lines. It discusses this in the Sureflo manual.