Pump keeps running

[CBabbs]

My water pump keeps running even when I'm not calling for water. I've checked all faucets and they are closed. The water level in the tank is low and I'm thinking that it may be running to rebuild pressure but I'm a bit leery of letting it run too long. Ideas?

[Jammer]

In general, if the fresh water tank runs out of water, the pump will run and will not shut off.

[Phoenix]

You probably have air in the lines from low water level. Most systems will accept a few extra gallons of fresh water without over-filling the black and gray water tanks. I'd try adding water from a 5-7 gallon portable tank to the fresh water supply to see if the water pump stops. Otherwise, time to dump and refill the tanks.

Note: We always carry a little extra fresh water in a portable tank, exactly for this reason. Also, it can allow an extra shower, an extra day or two of boondocking, or be a backup for some other emergency purpose. A little math to calculate the capacity of your black and gray water tanks will let you estimate how much extra fresh water you can run through the system without overflowing the waste water tanks.

[JDS]

I had intermittent running of the water pump when not running water and it proved to be a slow leak in the hpt water heater drain valve. You may have a hidden leak somewhere.

[AWCHIEF]

Sounds like the pump is just sucking air. That is what mine was doing when I first got it. The previous owner usually only used water from hook ups and rarely used the onboard tank. There was a lot air in the lines that needed to be purged after filling the tank. Not to mention it had a bit of an nasty smell from not being used enough to keep it fresh and clean.

[TG Twinkie]

Fill the FW tank. Then try it. If it still runs on. Shut it off, disconnect the discharge line from the pump. Start the pump and run it long enough for water to squirt out. Then re connect the line to the discharge side of the pump. Open a faucet and give it a try.
This process is called priming the pump.

[TBRich]

If it's running continuously with all faucets off, your fresh water tank is probably too low and it's taking in air from the tank rather than water... This will be different behavior than a slow leak in the line somewhere, which will usually result in intermittent surges of the pump as the system loses pressure and then pumps to restore pressure. As mentioned above, once you have air in the system you will need to purge it in order to have a smooth running system and avoid knocking water lines. When this happens to us I usually run the shower as it's the highest point in the system...if you do this several times it will usually self-correct and your system will run smoothly and more quietly when the air is gone.

[Uzzah]

And of all the above fails, you may have a bad pump. This same issue happened to me. the previous owner let water freeze in the system, and it damaged the pump. IT only worked at half capacity and would not build pressure and shut off. I had to replace the pump.

[CBabbs]

Thanks to everyone for the help. I filled the tank, bled from the shower and it seems to be back to normal.