water pump runs continuously

[JustinChase]

If my holding tank is full, all is well. Once the level of the water in the tank drops below the pump, my pump will start to occasionally run continuously, until I turn on a faucet, then it will prime and start moving water.


As the water level drops, it gets worse. Once I'm down to about 15% full, it won't prime and will just run continuously. If I get it primed, it will pump the tank completely if I let it. It's only when I turn off demand that the pump runs without priming.


I've replaced with a new pump but it does the same thing.


I called Shurflo and he said he has no explanation and no suggestions to try to fix this


I have checked and the inlet screen is clean, and it doesn't seem to be sucking air anywhere, and the pump isn't leaking.


I have no idea how to proceed from here.

[Dave A]

I though I was the only one that weird things happened to!

I'm wondering if the fresh water tank is venting? Can you see the tank? If the pump was taking water out and the tank wasn't venting it would surely be collapsing the tank.

Our old camper had the Nautilus system of valves and it acted up once and one of the valves was cracked internally.

What kind of RV do you have? Old or New?

[DutchmenSport]

If yours has a winterizing system, you might check the valve that turns winterizing on and off and make sure it's set to off. I have (on many occasions), flipped the wrong valve. Another thing, if you are filling your fresh water tank, make sure you flip the "fill" back to the normal "run" position and not keep in the the "fill" (fresh water tank) position. This will also keep the water pump running constantly. Check both valves. I but one or the other is flipped in the wrong direction after you have finished filling the fresh water tank.

[JustinChase]

My water heater was leaking, so I replaced it.


I was hoping the leak was the problem, but it was not, the situation continues.


My RV is a 2003 Carriage Carri-Lite, which has no water panel. I have a cap I remove to fill the tank, then replace the cap when full. There is an air inlet hose at the top of the tank, which appears to run to an opening next to the filler cap. As a test, I removed the hose and fitting from the top of the tank, in case it was clogged. No improvement.


I removed the hose from the inlet on the pump and lowered it below the outlet at the bottom of the tank, and water flows, but very slowly. I can't tell if this is an issue with a clog/partial clog, or a function of the tank being close to empty.


The only thing I can think to try next is to remove the hose and fitting from the bottom of the tank and replace it all; the fitting, the hose, the shut off valve and the hose to the water pump inlet.


Seems extreme, but I'm out of ideas. If the water doesn't flow from the bottom of the tank, what else could be the issue?


While testing this, I opened the shut off for the winterization hose, which is tee'd off after the tank shut off, so it shouldn't have any effect, but when I open it, the water surged out of the tank line for a second, then went back to a trickle. I'm not sure if this even matters, but I did find it weird.



I've opened every faucet, outdoor shower, and laundry hoses and bled off any air (as best I could.)


When I removed the inlet from the bottom of the pump, there was no water in the line from the tank to the pump, which surprised me. I assumed (I know) that once the system was pressurized, it would hold that pressure, but perhaps that's only after the pump and it's normal for the water to drain back into the tank from the inlet of the pump.


When the tank is full, the pump comes on almost instantly when I open a faucet and shuts off almost instantly when I close the faucet. Once the tank gets below the level of the inlet on the pump, it takes longer for the pump to kick on, and runs longer after I shut off the faucet. When it drops below 25% full, I have to leave the faucet running until there is almost no flow (a minute or more) before the pump finally kicks on and it takes another minute or more for the pressure to get to "normal".


It sure feels like this isn't normal, but maybe I'm just expecting too much and this is just how it is.


I'm tired of having to fill the tank every day, and I can' t leave it hooked to city water since it gets below freezing regularly here now.





Appreciate any more help or suggestions.

[DutchmenSport]

What you just described sounds like you might have a cracked line between the water tank and the water pump. And it sounds like the cracked line is that portion of pipe that is inside the water tank.

If the "outbound" hose is cracked (long ways), it sounds like the crack is completely covered with water when the tank completely full. Therefore, there is no way possible for air to enter the system.

As you use the water out of the tank, the water level lowers. Once it lowers to where the crack starts, your pump is not only pulling water, but also pulling air and thus, the longer cycle times.

As the water drops even lower, the crack is allowing more air into the lines, until finally, when the water reac hes a certain point at a low level, the pump is actually pumping more air than water, and thus, loosing it's prime.

From what you described above, your water line is cra ked. The cracked line in that portion of line inside the tank.

The end of that pipe should be almost touching the bottom of the lowest point in the tank. So, there's probably 8 inches to 12 inches of hose inside the tank, depending on how thick the frame of your trailer is.

This is what it sounds like to me, after your description above.

[JustinChase]

I've attached a photo of the water tank and the plumbing from the tank to the pump from before. The hose coming out of the bottom (on the right) has a multi-turn shut off, then a tee with another shut off going to the hose used to winterize and the straight run from the tee goes into the bottom of the pump.

I removed the fitting at the bottom of the tank and replaced it with a new fitting, a new short piece of pex into a ballcock into the hose to the water pump, eliminating the tee and the winterization hose, as a test. (2nd photo)

When I started filling the tank, I turned on the bathroom faucet (the highest in the RV) and the pump started right up and shut right off again. Great.

I then turned on the kitchen faucet and it had no pressure and took a long time for the pump to kick on, then to shut off again, just like before.

I mentally gave up and just filled the tank, since it's snowing, getting dark, and I have no more energy for this today.

There is no hose in the tank, and I've replaced everything from the outlet to the pump. Well, I kept the white hose from the ballcock to the pump, so I guess it could be that. I can replace it easily enough since it's after the ballcock, and I may try that tomorrow. I don't think I can connect the pump filter to pex, so I'd have to replace it with new vinyl hose. I purchased a camco water hose (on clearance at Lowes) while buying new fittings, to cut into lengths to do this replacement.

If that doesn't do it, I'm literally out of ideas, as everything from the tank to the pump will be brand new, and doesn't appear to be leaking.

It feels like it shouldn't be this hard, but that which doesn't kill you makes you stronger; I guess