Water Pump

[Shat]

Water pump works as expected until water level in fresh water tank drops down to appr. 1/3, then water pump continues to run after faucets are shut off. Pump does shut off when you shut the switch off. What doesn't make sense is the issue isn't present if the fresh water tank is above 1/3 full.

I'm wondering, does the pump sit higher than the fresh water tank and once the water level drops so low the pump wants to keep drawing water up since gravity is no longer keeping water in the pumps inlet hose? If that is the case would a hose with a few loops in it ran from the water tank outlet to the pump inlet fix this? Maybe it's just an inferior pump, even though rv is just 1yr old? 2024 keystone passport.

I'd appreciate any feedback especially if you've experienced this and know how to fix it.

 

[jxnbbl]

Water pump works as expected until water level in fresh water tank drops down to appr. 1/3, then water pump continues to run after faucets are shut off. Pump does shut off when you shut the switch off. What doesn't make sense is the issue isn't present if the fresh water tank is above 1/3 full.

I'm wondering, does the pump sit higher than the fresh water tank and once the water level drops so low the pump wants to keep drawing water up since gravity is no longer keeping water in the pumps inlet hose? If that is the case would a hose with a few loops in it ran from the water tank outlet to the pump inlet fix this? Maybe it's just an inferior pump, even though rv is just 1yr old? 2024 keystone passport.

I'd appreciate any feedback especially if you've experienced this and know how to fix it.

Sounds like the inlet in the tank starts sucking air at 1/3 full....

 

[workinonit]

Just because that cheesy display says there's 1/3 tank doesn't mean it's not empty.

 

[NH_Bulldog]

It could very well be one or a combination of the issues noted above. Also consider that with the newer tanks having more and more capacity than even just a few years ago, they have gotten longer, wider and flatter. Because of this, there is little physical distance between the sensor pins. Like any tank gauge, these readings should only ever be considered as a guide and should not be relied on for any accuracy.

On my previous camper, the tank was forward of the axles and the amount of water in the tank affected the tongue weight and handling characteristics, so I always used a flow meter when filling the 30 gallon tank. I liked to carry 10 gallons when traveling for bathroom breaks, hand washing, and water emergencies on the road. The gauges didn't read 1/3 full until I had 20 gallons in the tank, 2/3's at about 26 gallons and full at 29 gallons, go figure right? I found that if he camper wasn't level at a rest stop I was okay if it was leaning toward the driver's side, but would suck air if even an inch out of level leaning towards the passenger side.

My current camper has a 56 gallon fresh water tank and it is behind the rear axles and water weight really doesn't affect anything for me now. I now carry around 25 gallons so we can have water even if we have to make an unplanned overnight stop. Based on my testing with this unit, the gauges are "reasonably" accurate, but again, I prefer to go by what I know goes in, versus our past experience on how much water we use in a given period of time.

This is what a typical fresh water tank looks like. Those pins (really just screws) are not added by the tank manufacturer using any sort of standardized template for their location. The RV manufacturer adds the pins themselves at the time they install the tank since the same tank is used in many different trailer floorplans.

 

[JRTJH]

Most water tanks, both fresh and holding tanks are rectangular, span across the trailer frame and usually are only about 5 or 6 inches tall. So if they are not level and if the trailer is not level side to side, the water will also flow to the low side of the tank, preventing the pickup to be above the water level inside the tank.

On some tanks, the "pickup hole for the pump is located at the bottom of the tank, usually about an inch above the bottom. When that hole starts drawing air, the pump will no longer draw water from the tank. The ENTIRE hole must be below the water line to draw water to the pump. If the trailer is not level (low side away from the pump pickup hole) then the water level will be lower on the pump pickup and cavitate sooner leaving water in the tank.

On some installations, there is a "pickup tube" inside the water tank that SHOULD have the end located at the lowest point inside the tank. On most tanks, that's a small "sump space" molded into the bottom of the tank. The tank drain valve/cap is also located in that sump. If your tank is not installed "level" then the water will not always completely cover the pickup tube opening. If it's not completely submerged below the water level, it will suck air and lose the ability to pull water to the pump. Here's a diagram of how the pickup tube looks inside the tank.

The second drawing shows the basic shape of the fresh water tank for most modern trailers. You can see the "sump molding" at the bottom end of the tank. That's where the pump draws water on a direct connection (without a pickup tube inside the tank). As you can imagine, if the tank is not level, water will flow to the other end of the tank and air will cause the sump to be above the water level and the pump will start to cavitate.

Your issue may be a "short pickup tube", a tank that's not installed level, the trailer not being level on the campsite, or even a "sensor nail" that is not in the correct location and is showing 1/3 full when in reality it's a combination of all of the above that's causing the indicator to not be accurate.

 

[DutchmenSport]

Hold the phone! Stop the traffic! Turn off the television! Hold the race horse one second longer......

Before doing anything, (IF) your water is filled from the garden hose and the garden hose has to be connected to an inlet, and a valve has to be switched from the "Normal" to the "Fill" position .... then make sure, after you are finished filling your fresh water tank you put that valve back into the "Normal" position and do not leave it on "fill". That's all you have to do.

Now, if your camper is a gravity fill water tank, you cannot depend on the sensors and push buttons inside the camper. Those are not reliable, are very misleading, and most of the time, simply do not work.

What you need to do is get an in-line water meter (used on a garden hose) and attach it and actually determine how much water is being filled in the tank. My guess is, your water tank is truly empty, and the pump is just sucking air. You won't know unless you can actually measure how much water it takes to fill the tank.

Still..... if you have the valve.... after filling, flip it back to "normal". Believe it or not, I did this just a couple days ago. I filled my tank and forgot to flip it back to "normal." Pump ran just fine until the water got low. Then the pump ran and ran and ran. I was frustrated thinking something was going wrong. Finally, I caught it ... I forgot to flip the darn valve (again!).... OK.... it's been a few months since I did that ... but dang... it make you feel like an idiot when it happens!

 

[Peto]

When it starts to lose prime. Pull the dump handle on the fresh tank and see how much water comes out. It may just be empty.

 

[Shat]

Most water tanks, both fresh and holding tanks are rectangular, span across the trailer frame and usually are only about 5 or 6 inches tall. So if they are not level and if the trailer is not level side to side, the water will also flow to the low side of the tank, preventing the pickup to be above the water level inside the tank.

On some tanks, the "pickup hole for the pump is located at the bottom of the tank, usually about an inch above the bottom. When that hole starts drawing air, the pump will no longer draw water from the tank. The ENTIRE hole must be below the water line to draw water to the pump. If the trailer is not level (low side away from the pump pickup hole) then the water level will be lower on the pump pickup and cavitate sooner leaving water in the tank.

On some installations, there is a "pickup tube" inside the water tank that SHOULD have the end located at the lowest point inside the tank. On most tanks, that's a small "sump space" molded into the bottom of the tank. The tank drain valve/cap is also located in that sump. If your tank is not installed "level" then the water will not always completely cover the pickup tube opening. If it's not completely submerged below the water level, it will suck air and lose the ability to pull water to the pump. Here's a diagram of how the pickup tube looks inside the tank.

The second drawing shows the basic shape of the fresh water tank for most modern trailers. You can see the "sump molding" at the bottom end of the tank. That's where the pump draws water on a direct connection (without a pickup tube inside the tank). As you can imagine, if the tank is not level, water will flow to the other end of the tank and air will cause the sump to be above the water level and the pump will start to cavitate.

Your issue may be a "short pickup tube", a tank that's not installed level, the trailer not being level on the campsite, or even a "sensor nail" that is not in the correct location and is showing 1/3 full when in reality it's a combination of all of the above that's causing the indicator to not be accurate.

Thank you. Even though I'm disappointed with the design flaws, it is what it is. The sensor being inaccurate would not be shocking as we know it's inaccurate on gray and black tanks. However, when the pump started ceasing it's auto shut off we did open the low point drain and water was still in the tank and continued to empty for some time. We didn't catch and measure but may next time, just to see. All this information is very helpful. We will just refill the fresh water tank when we notice the pump not shutting off.

 

[Shat]

Hold the phone! Stop the traffic! Turn off the television! Hold the race horse one second longer......

Before doing anything, (IF) your water is filled from the garden hose and the garden hose has to be connected to an inlet, and a valve has to be switched from the "Normal" to the "Fill" position .... then make sure, after you are finished filling your fresh water tank you put that valve back into the "Normal" position and do not leave it on "fill". That's all you have to do.

Now, if your camper is a gravity fill water tank, you cannot depend on the sensors and push buttons inside the camper. Those are not reliable, are very misleading, and most of the time, simply do not work.

What you need to do is get an in-line water meter (used on a garden hose) and attach it and actually determine how much water is being filled in the tank. My guess is, your water tank is truly empty, and the pump is just sucking air. You won't know unless you can actually measure how much water it takes to fill the tank.

Still..... if you have the valve.... after filling, flip it back to "normal". Believe it or not, I did this just a couple days ago. I filled my tank and forgot to flip it back to "normal." Pump ran just fine until the water got low. Then the pump ran and ran and ran. I was frustrated thinking something was going wrong. Finally, I caught it ... I forgot to flip the darn valve (again!).... OK.... it's been a few months since I did that ... but dang... it make you feel like an idiot when it happens!

Ours is gravity fill but we have been warned to make sure the winterize switch has been switched off.