water pump not holding

Max23 · 05-14-2023, 06:01 AM

So, water pump works. Pumps up to pressure and shuts off. Then you hear what sounds like water running (lightly) soon the pump kicks back on up to pressure and shuts off. Sounds like a water leak yes? Well, kicker is, no leaks anywhere that can be found, not wet spots nothing. Guessing the water is leaking back into the holding tank from through the pump. Only explanation I can come up with anyway. Now, the question is, is this even a possibility? What else could it be? Need to replace pump?

**chuckster57** · 05-14-2023, 06:42 AM

I would be looking behind shower faucet, outdoor shower faucet just to rule them out. How long after it gets to pressure does it run again?

NH_Bulldog · 05-14-2023, 07:12 AM

Usually at the beginning of the season mine will not hold pressure for more than a few hours. Then I run the pump through a few cycles, full open, partially open, off, on and repeat with all faucets open. That seems to exercise the system enough and it holds pressure the rest of the season

**JRTJH** · 05-14-2023, 08:19 AM

If the water pump pressurizes the system then bleeds down enough to cause the pump to cycle (burp) occasionally, then one of two things is happening.

1. There is a leak in the trailer plumbing. It may be a loose connection at a faucet, a "freeze damaged fitting" or a leaking "one way valve in the city water inlet"...

2. There is a leak in the pump diaphragm, which serves as the "one way valve" for the pump. It's intended to stop water flow back through the pump and into the fresh water tank....

As bulldog stated, at the beginning of the season, the diaphragm may not be "fully pliable" until it gets completely filled and softened by water flow over it for a period of time.... Or, it may have some trash that was sucked up the fresh water suction line from the tank to the pump head.

What some people don't realize, is that "superchlorinating the fresh water tank" as a means of sanitizing the system, if done "over-zealously" by adding too much chlorine, it can "dry out the diaphragm" which can make a "marginal diaphragm" fail quicker than it might have otherwise failed....

I'd watch the pump for a day or so, see if it stops "burping" after it gets "completely wet". If it continues, I'd look for a leak in the plumbing. Start by checking all the faucet fittings for looseness, then if it continues, start looking for a leak at one of the plastic elbows or "Y" fittings.... Don't forget to check the outside shower. Just a little leak there from storing the spray head against the faucet handle can cause a pump to "burp" regularly.....

Max23 · 05-14-2023, 08:34 AM

Thanks, I also thought a out debris getting caught in there. Has been used on about 4 outing already this year with no problem so it's had time to reseal from the winter, just started up. Have looked everywhere for leaks, just bewildering. Gonna have to check for debris in the diaphragm I guess. Or, yes diaphragm failure. Thanks for the insight guys! Appreciate it.

**JRTJH** · 05-14-2023, 06:15 PM

A pump strainer is one of the best investments anyone can make for their RV plumbing system. The FloJet strainer, last year, was $7. This year, they're roughly $15, but still a "bargain" when compared to taking a pump head apart to clean it out or buying a replacement pump, which now runs closer to $100 than to last year's price of $59.

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

bobbecky · 05-14-2023, 07:59 PM

The diaphragm isn't the pressure holding component but there is a separate check valve that hold the water from seeping back to the water tank. It's very likely the valve has failed or there is debris in the valve not allowing it to fully close. Most pumps have the check valve able to be replaced or removed and cleaned. This is a Shurflo pump with the pressure switch and the check valve indicated with arrows. Other brands will be similar.

FlyingAroundRV · 05-15-2023, 02:46 AM

Quote:

Originally Posted by bobbecky

The diaphragm isn't the pressure holding component but there is a separate check valve that hold the water from seeping back to the water tank. It's very likely the valve has failed or there is debris in the valve not allowing it to fully close. Most pumps have the check valve able to be replaced or removed and cleaned. This is a Shurflo pump with the pressure switch and the check valve indicated with arrows. Other brands will be similar.

I was going to post the same thing but bobbecky beat me to it.
There's a chance that the non-return valve in the pump head is stuck partially open. Don't be afraid to take the pump out and take the head off it. They are simple beasts and nothing will spring out and fly away..
In the pump head, you will see a little round plunger sort of a thing that when you press it, has a light spring tension on it. When released, the plunger should be level with the surrounding surface. That is, it should not sit below the surrounding surface.
Push the plunger in and let it spring back a couple of times and it should clear whatever is obstructing it.

Max23 · 05-15-2023, 03:47 AM

Ahhhhhh, ya. Thanks all, that helps tons.

Max23 · 05-15-2023, 03:53 AM

Not sure when he'll get to it but sending all the info. I know he has a flojet pump so I'll try n let you know what is found. Thanks again.

NH_Bulldog · 05-15-2023, 04:17 AM

I added a screen filter to mine after my first pump bleed-back issue. I still catch plastic bits from the tank after 4 full camping seasons.

**JRTJH** · 05-15-2023, 10:03 AM

Quote:

Originally Posted by bobbecky

The diaphragm isn't the pressure holding component but there is a separate check valve that hold the water from seeping back to the water tank. It's very likely the valve has failed or there is debris in the valve not allowing it to fully close. Most pumps have the check valve able to be replaced or removed and cleaned. This is a Shurflo pump with the pressure switch and the check valve indicated with arrows. Other brands will be similar.

You are correct that the ShurFlo pump has a separate check valve assembly but the FloJet pumps DO NOT have a separate check valve. On FloJet pumps, the check valve is nothing more than a rubber "flapper disc" mounted on top of the diaphragm, inside the pump head. In this diagram, you can see it as "part 13" Any trash that gets into the diaphragm (part 12) can/will cause that "flapper disc" to stay open and bleed back into the FW tank.

On FloJet pumps, it's all "in the diaphragm assembly, not a separate check valve"....

Max23 · 05-21-2023, 04:42 AM

Thanks for all the knowledge gents. He took it apart and sure enough, a little piece of plastic stuck in there holding it open. Strainer is in my near future I do beleive. Lol. Thanks again.

Domino3665 · 05-21-2023, 08:05 AM

Water and air do not leak equally. You could have air leaks without liquid leaks. I chased fuel leaks on C-130s and F-16s for years. (trust me.)
Crawl through your rig and snug EVERY fitting. Snug…not bone tight.
You might be surprised how loose some fittings are. My water pump used to run intermittently like most but after snugging fittings, it only runs when I open a faucet. Mo’ betta’.

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