How to pressure test a domestic 12v fresh water pump?

[NealB]

The latest job, was to identify the leak in the domestic fresh water supply, somewhere between the two stainless tanks and the three sinks.

After much swearing, and poking around in unergonomic, inaccessible, places, I found that the outlet spigot of the Jabso electric pump, was weeping profusely.

So I removed the spigot (a nice easy job: just push up the blue locking, then pull), and replaced the rubber seal.

Lovely, except the pump now doesn't draw water up from the tanks.

I took the pump off, and stuck its inlet spigot in the galley handbasin: no problem, water gushed out like a good'un. I put a finger over the outlet spigot, and the pressure cut the pump off: all hunky dory.

Hmmmm ...... I put the pump back in it's usual spot, and it still didn't prime.

The pump is only about a foot above the top of the tanks.

The label says it's rated at 25 PSI, but I've no real idea of what that feels like.

Do these pumps get less effective with age? Might it have lost the energy to lift water?

Very odd: as it seemed to prime yesterday (albeit leaking on the output side).

Are there more robust tests that can be easily done, or is it worth gambling around £200 on a replacement pump?

It's not this exact model, but it looks this: Jabsco Parmax HD4 12V 25Psi Pump

 

[greeny]

You've had the pump off to test it so assume you've disconnected both the inlet and outlet. Is the inlet now leaking and sucking air in, preventing it priming. Check the rubber seal and a small smear of silicon grease may help.

 

[Meps1983]

I had a problem with my jabasco earlier in the summer. It would work fine with the tank full, but once it got down to about 1/3 remaining it would keep often fail and leave the pump running, but not priming!
I couldn't see any drips or hear any air leaks but I did notice bubbles in the strainer that connects to it. Turns out a previous owner had tried to remove the strainer cracking it in the process. Then kindly repairing it with a smudge of silicone of the top of the crack! Anyway replacement strainer and now she works better than before.
Not sure of if I've done the pic right of their handy work

 

[NealB]

You've had the pump off to test it so assume you've disconnected both the inlet and outlet. Is the inlet now leaking and sucking air in, preventing it priming. Check the rubber seal and a small smear of silicon grease may help.

Thank you!

Yes, removing the inlet and outlets are both dead easy (a matter of seconds for each one). I replaced both rubber seals.

When the inlet side is put in a sink of water, and power applied, water gushes forth.

 

[NealB]

I had a problem with my jabasco earlier in the summer. It would work fine with the tank full, but once it got down to about 1/3 remaining it would keep often fail and leave the pump running, but not priming!
I couldn't see any drips or hear any air leaks but I did notice bubbles in the strainer that connects to it. Turns out a previous owner had tried to remove the strainer cracking it in the process. Then kindly repairing it with a smudge of silicone of the top of the crack! Anyway replacement strainer and now she works better than before. View attachment 182414
Not sure of if I've done the pic right of their handy work

Thank you!

There's a couple inline strainers, before the pump inlet side, and I guess they're the next things to test.

But, wow, it's SO boring now: I just want to do a bit of sailing!

Actually, tomorrow, I'll rig up a test where the pump has to lift water straight from a bucket, with no strainers.

I just wonder whether it'd be possible to rig up some sort of pressure gauge on the outlet side, to see if it's anywhere the claimed 25 psi. Something a plumber might be able to do?

 

[Metalicmike]

25psi is not that hi, your mains can get up to 45psi at night,

12.5 ltrs/hr self priming 35psi 75 quid on amazon.

 

[NealB]

25psi is not that hi, your mains can get up to 45psi at night,
View attachment 182419
12.5 ltrs/hr self priming 35psi 75 quid on amazon.

Thank you ...... I might treat myself to a birthday gamble!

 

[Bodach na mara]

The simplest pressure gauge that you could use is a long length of transparent neoprene tube. Possibly you use some in your water system. You attach one end to the pump and the other to the main halyard and pull it up the mast. (I did say that you need a LONG bit of tube.)

Actually 25 psi pressure will push the water to a height of about 40 feet so you may need a taller mast, but, being serious for a minute, if you start the pump with the hose end on deck the water should gush out. If it is not still flowing steadily when you are standing on deck and holding the hose as high as you can, then the pump is faulty.

But your current problem has nothing to do with the output pressure. You have an air leak in your system somewhere between tank and pump.

 

[NealB]

Thank you ...... just the sort of visual explanation I can relate to.

So, tomorrow, I'll bypass the two inline filters, between the tank and the inlet side of the pump, and see if that improves things.

 

[oldgit]

Only greatly increase any new pump psi if you want to blow out all the connections in the system, just stick with what was there before.

 

[greeny]

How full is your water tank? The pump may only be slightly above the top of the tank but if the level is low, the pump is sucking from much lower down. The pump should be able suck from that low but if the pump is not 100% it may struggle to lift the water that high. Fill the tank and try again if its not full.

 

[NealB]

How full is your water tank? The pump may only be slightly above the top of the tank but if the level is low, the pump is sucking from much lower down. The pump should be able suck from that low but if the pump is not 100% it may struggle to lift the water that high. Fill the tank and try again if its not full.

How full is your water tank? The pump may only be slightly above the top of the tank but if the level is low, the pump is sucking from much lower down. The pump should be able suck from that low but if the pump is not 100% it may struggle to lift the water that high. Fill the tank and try again if its not full.

Thank you, but both tanks are brim-full.

 

[NealB]

I think I might be onto something.

On closer inspection, the top of the water strainer, attached to the inlet spigot, doesn't seat very well on its base. In fact, with the strainer removed, I can blow and suck air through the inlet of the strainer, with a finger over the outlet side.

So a new strainer should be delivered tomorrow.

Jabsco Fresh Water Pump Inlet Strainer Threaded

Finger crossed that'll fix things.

I'll report back.

 

[NealB]

The replacement strainer arrived this afternoon.

I slotted that in place on the inlet side, with the outlet side disconnected, then swithed the pump on, and ....... water gushed forth from the pump!

I switched off, and connected the outlet spigot to the hoses delivering water to the sinks and showers. I could see water passsing through the strainer, and after a few minutes it came up to pressure.

We tried all 6 taps, and ............water gushed forth!

With the taps off, it held pressure for about 90 minutes, with no cycling.

We got all the sections of the bilges absolutely bone dry: will check tomorrow.

So....... it looks hopeful.

Huge thanks for the collective wisdom.

Note to self: I must try hauling an outlet hose up the mast to test pump pressure, sometime, just for fun.

 

[Daydream believer]

25psi is not that hi, your mains can get up to 45psi at night,
View attachment 182419
12.5 ltrs/hr self priming 35psi 75 quid on amazon.

12.5 litre PER HOUR
I wee faster than that

 

[NealB]

12.5 litre PER HOUR
I wee faster than that

Well spotted and well weed (presumably, after an evening in the Station Arms?)