Pump will not re-prime after running out of water

[Outsider]

GeoPro G19FD with Pentair shurflo 4008-101-A65 water pump.


Here's how it happened:
Left home with 1/4 tank fresh water.
Stayed first night on the road at Cracker Barrel but camper was slanted nose down on a slight hill and ran out of water during the evening after having worked fine when we first arrived. I didn't realize it but the pump probably ran for 15-30 minutes sucking air.
Arrived at campground next day and used city water only and all was fine, of course.

Moved to this new campground today, 8 days later with electric only. Filled fresh water tank FULL with good water and now the self-priming pump will not prime.
That is the whole story, no other changes at all. Pump runs. Strainer is NOT clogged, but will not prime.


Thoughts? Don't go too deep. This should be simple.

[NavyLCDR]

How long have you ran the pump trying to get it to prime? It may take a while.

[Bob K4TAX]

Originally Posted by Outsider

GeoPro G19FD with Pentair shurflo 4008-101-A65 water pump.


Here's how it happened:
Left home with 1/4 tank fresh water.
Stayed first night on the road at Cracker Barrel but camper was slanted nose down on a slight hill and ran out of water during the evening after having worked fine when we first arrived. I didn't realize it but the pump probably ran for 15-30 minutes sucking air.
Arrived at campground next day and used city water only and all was fine, of course.

Moved to this new campground today, 8 days later with electric only. Filled fresh water tank FULL with good water and now the self-priming pump will not prime.
That is the whole story, no other changes at all. Pump runs. Strainer is NOT clogged, but will not prime.


Thoughts? Don't go too deep. This should be simple.

Pull the input water line off at the pump. See if you, by mouth, can suck water from the FULL good water in the tank. If so, put the connection back on the pump. It should prime.

If you can't get water likely the intake Line is blocked or is open thus allowing in air. Make sure the strainer is sealed and not allowing in air. (Ours froze and cracked. It had to be replaced.)

I've also seen where the fresh water tank vent is clogged thus the pump is trying to pull against a vacuum. In this case, open the fresh water fill cap, leave it loose, and see if the pump will prime.

Bob

[Outsider]

Thanks for the replys.
1) I have probably not let it run more that 3-5 min at a time multiple times as I tried various faucets and tricks. A) sealing the fresh water fill spout with my mouth and blowing into the tank for several minutes creating good pressure in the tank. B) creating a vacuum at the kitchen faucet by sucking air from that spout. C) running the pump for 30 sec on, 30 sec off for 10 or so cycles. D) pulled the intake screen bowl at the pump to check for clogs. Now that I think about it, there were only a few drops of water in that screen bowl when I pulled it off.


2) As suggested I'll pull that hose off at the pump intake tomorrow and see if I can suck water up or if I only suck air. I'll also check closer for cracks in that bowl but we should be good there as it worked fine until I ran it dry 8 days ago.


My thought is perhaps the pump diaphram area got too hot having run dry for 15-30 minutes back at Cracker Barrel and then deformed.

[JimM2109S]

If a winterization valve is installed on your camper, make sure that it is fully closed.

[Outsider]

Doesn't come into play here. System worked fine 8 days ago until I ran it dry. No other changes. Thanks.

[MGD1961]

Originally Posted by Outsider

Thanks for the replys.
1) I have probably not let it run more that 3-5 min at a time multiple times as I tried various faucets and tricks. A) sealing the fresh water fill spout with my mouth and blowing into the tank for several minutes creating good pressure in the tank. B) creating a vacuum at the kitchen faucet by sucking air from that spout. C) running the pump for 30 sec on, 30 sec off for 10 or so cycles. D) pulled the intake screen bowl at the pump to check for clogs. Now that I think about it, there were only a few drops of water in that screen bowl when I pulled it off.


2) As suggested I'll pull that hose off at the pump intake tomorrow and see if I can suck water up or if I only suck air. I'll also check closer for cracks in that bowl but we should be good there as it worked fine until I ran it dry 8 days ago.


My thought is perhaps the pump diaphram area got too hot having run dry for 15-30 minutes back at Cracker Barrel and then deformed.

Pump is done. Quit flogging it and go buy one.

I think you are exactly right. That much dry run time put a hole in the diaphragm

[NMWildcat]

Originally Posted by MGD1961

Pump is done. Quit flogging it and go buy one.

I think you are exactly right. That much dry run time put a hole in the diaphragm

It's possible that the pump is bad, or fouled, but I doubt it is from that short time of running dry.. RV water pumps have been designed to run dry without damage. I have run mine dry several times overnight, with the longest period of 3 days. Pump still works fine.

When priming my system after being dry, it occasionally take 10-15 minutes to prime. I usually have to open/close a faucet to get things going. Other times, it primes right away. Go figure.
Hopefully the OP gets his system figured out and lets us know his solution.

[Aussieguy]

diaphragm pumps usually don't need priming

if yours is not pumping ...

a) put hand /finger on pump and feel if it is vibrating
no vibration could be a pressure switch

b) inspect the rubber diaphragm make sure no tears /dirt buildup

if you find a torn diaphragm all you need to do is replace that part.
no need to buy a whole new pump.
Repair kits are available

here is the manual ... has a troubleshooting section
https://www.pentair.com/content/dam/...s-pump-iom.pdf

[MGD1961]

How much is you time worth. Go to Walmart or some camper store or a marine store and buy a pump.

Or spend the rest of your time playing with an old pump that probably should be replaced anyway.

[NMWildcat]

Originally Posted by Aussieguy

diaphragm pumps usually don't need priming
....

Priming in a traditional sense (pouring water into the pump itself) no. Priming, as in pulling water from the tank to the pump, yes.
My pump has to pull water up a few feet and across for about 20'. It takes awhile. And it seems to help if I open a faucet. But then it could just be coincidence
The one time I could not get it to prime (in the RV sense), I took it apart and found it was full of debris. Cleaned it up, worked fine. These little pumps are fairly bulletproof.

[NMWildcat]

Originally Posted by MGD1961

How much is you time worth. Go to Walmart or some camper store or a marine store and buy a pump.

Or spend the rest of your time playing with an old pump that probably should be replaced anyway.

And the other side of that story is that if it is a leak, suction, debris, or technique problem, then you have an extra pump with the same problem

[MGD1961]

Originally Posted by NMWildcat

And the other side of that story is that if it is a leak, suction, debris, or technique problem, then you have an extra pump with the same problem

True. On the other hand the OP said it worked. They ran it dry. Then it didn’t work. We can all find someone to agree with us if we look hard enough. Chances are it’s the pump. Maybe not. If I were there I could tell you in about 2 minutes with a clear confident diagnosis. But I’m not. So my opinion is put a pump in it and hurry. Beer o clock is coming. Let little problems be as little as possible. That’s all I’m saying. If you have all the time in the world and feel like playing with it all day. Go for it. And then go buy a pump.

[GolfingDave]

Do these pumps have a weep hole if the diaphragm is bad?

[NMWildcat]

Originally Posted by GolfingDave

Do these pumps have a weep hole if the diaphragm is bad?

Attachment 297426

My knee-jerk answer is no.
But honestly, I don't remember ever looking specifically for one.
And of all the bad pumps I have replaced, the only one I remember leaking from the pump itself was a friend's pump. He had stripped all the screws when putting it back together. He likes to use power tools for everything

[jimmoore13]

Three possible ways you might prime...at the pump.

IF you have a winterization valve, there is likely a short clear hose attached. Hold the hose upright without kinking and fill it with water. Turn the winterization valve to take water from the hose instead of the fresh tank. Run the pump for a couple of seconds to get that water into the pump. Then switch back to drawing from the fresh tank. Water in the pump will greatly increase the suction from the pump, and it may be able to "lift" the water out of the tank.

If you DON'T have a winterization valve, look for the intake screen on the pump. You should be able to rotate the filter housing so the clear plastic cap is facing "up." Remove the cap and screen (and clean the screen), and then place a catch pan below the filter housing. This will be a bit messy. You'll need at least one helper to operate the pump switch. Using a funnel or similar, start pouring water into the filter housing, turn on the pump for a moment and catch prime. NOTE: the lion's share of this water will go down into your fresh tank, so keep things clean. But the pump should be able to suck some water those few inches. Replace the screen and clear cover, and try pumping from the fresh tank.

You might also try pouring a bit of water into the output of the pump. This may be more difficult, but that would also work.

As pumps wear...and as they dry out...the seals in the pump need water to complete the seal and suck water up out of the tank. Manually priming may restore function. Once you catch prime, the check valve in the pump will likely keep things wet to make the pump function well. But when things dry out, an older pump "doesn't suck" as they say.

I had an old farmhouse (1837). The shallow well would sometimes run "dry"...the pump pickup would be exposed. I had a "jet" pump...up inside the house. Unlike an in-the-well pump, a jet pump sucks rather than pushes the water out of the well. As the pump aged, it would sometimes not be able to catch prime. I kept several sanitary gallon containers of water on hand to prime the pump. As I added water to the pump, suction increased considerably, and the pump could suck water the 90 feet up from the well.

Those old hand-pump pitcher pumps function the same way. They "suck" water from the well, and the gaskets in the pump were often leather, so they'd wear and dry out quickly.

If you lose prime again, buy a new pump.

[Outsider]

Quick update here by the OP.



I still do not know what the exact problem is but I have proven that it is not the pump. If I disconnect the 3 tee'd lines going into the pump and connect a water line directly from the pump intake to a jug of water it works as it should, no problem.



( As mentioned, I am currently on the road so I hope to finish the trouble shooting early next week when we get home.)


I'm not sure what each of the lines going to the intake side is or which is which. One is from the fresh water tank of course, one is an anti-freeze intake and the third "may" be coming back from the shower doing that funny hot water recycle trick so that you don't waste hot water.


Apparently the pump is sucking air from one of those 3 lines when everything is fully connected.

[rracer5]

Originally Posted by Outsider

Quick update here by the OP.



I still do not know what the exact problem is but I have proven that it is not the pump. If I disconnect the 3 tee'd lines going into the pump and connect a water line directly from the pump intake to a jug of water it works as it should, no problem.



( As mentioned, I am currently on the road so I hope to finish the trouble shooting early next week when we get home.)


I'm not sure what each of the lines going to the intake side is or which is which. One is from the fresh water tank of course, one is an anti-freeze intake and the third "may" be coming back from the shower doing that funny hot water recycle trick so that you don't waste hot water.


Apparently the pump is sucking air from one of those 3 lines when everything is fully connected.

Never heard of that "trick" so, I wouldn't spend too much time trying to figure out what that's all about. But, it looks like you're on the right track looking for an air leak. If you can, try filling all the lines attached to the pump with water. Also, blow into the suction line from the FW tank. There could be plastic debris from drilling for the plumbing blocking the tube in the tank.

[Outsider]

Will report back next week. Thanks.

[NMWildcat]

Originally Posted by rracer5

Never heard of that "trick" so, I wouldn't spend too much time trying to figure out what that's all about. But, it looks like you're on the right track looking for an air leak. If you can, try filling all the lines attached to the pump with water. Also, blow into the suction line from the FW tank. There could be plastic debris from drilling for the plumbing blocking the tube in the tank.

The "trick" is called a Shower Miser that some RVs come from the factory with. Some seem to to be plumbed differently than the manufacturer (Shower Miser) recommends. I have heard of some having this problem if the Miser valve is turned to the 'return' setting. The OP might check that all the shower valves are in the closed position (including Shower Miser).