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Old 14-01-2018, 10:21   #1
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Fresh Water Pump Not Producing Rated Output

I was working on the plumbing because I thought I had a clog somewhere and I got around to testing the output of my freshwater pump. I found that I am getting far less output even though there is no clog in the system - itís a West marine pump rated at 4 GPM but Iím getting closer to 1.2 gallons per minute. Otherwise, the pump is behaving normally.

Iím trying to figure out if there is something wrong with the pump.

- We do have an inline filter so I removed it (5 micron pleated) and only saw very little improvement.. maybe 1.5 GPM

- I did open the pump (link to pump below) to check for clogs or other problems but as far as I can tell, it looks ok. It still pumps and it doesnít leak or anything.

- The water level in the tank is about three feet below the faucet.

- we use 1/2Ē PEX plumbing. I checked for clogs by taking the high pressure dock side water and building an adapter so I could shoot the water into the piping opposite of the normal piping. It appeared to be fine.

- I switched to a second tank that sits lower and shares only a small portion of the piping with the other tank and had the same results.

- I bypassed the tanks and the filter unit all together and ran a piece of PEX from a bucket near the pump to the pump. Pretty much the same results.

- I ran the dock hose into the inlet side of the pump and turned it on. Got great pressure.... better than the pump.

- We are plugged into the dock.

- I checked the voltage to the pump. It reads 12.69 volts. The batteries are floating at 13.05 or 13.1 or so as measured by my SmartGauge.

http://www.westmarine.com/buy/west-m...4gpm--14153266

So I guess my questions are... do pumps like this one gradually die? Is it normal to get such low output from a GPM pump? Is there something in the pump head I should look at more closely?

Thanks..
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Old 14-01-2018, 18:47   #2
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Re: Fresh Water Pump Not Producing Rated Output

Pumps are I believe rated at zero lift and zero pressure, with zero line loss.
However I wouldnít expect such a large drop as you have.
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Old 14-01-2018, 19:02   #3
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Re: Fresh Water Pump Not Producing Rated Output

That looks like a three chamber "wobble plate" pump. One or two of the intake valves may be shot. They make rebuild kits for them - maybe not from West Marine, but from the manufacturer. (Shurflo ?)
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Old 15-01-2018, 04:43   #4
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Re: Fresh Water Pump Not Producing Rated Output

An air leak, on the pump inlet side, will cause low flow & pressure.
It's a Jabsco 'Par-Max' ➥ http://www.xylemflowcontrol.com/file...43000-1810.pdf
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Old 15-01-2018, 05:36   #5
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Re: Fresh Water Pump Not Producing Rated Output

Probably something caught in one or two of the valves in the pump. Disassembly should reveal the situation. It may be debris from the tank, especially if you don't have a strainer, or it could be burs or whatever from when the plumbing was assembled.
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Old 15-01-2018, 08:58   #6
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Re: Fresh Water Pump Not Producing Rated Output

Usually leaking valves etc result in excessive run times before the thing shuts off, you use just a little water at the sink and the pump normally runs three or four sec, leaking valves, it runs for 30 sec or more.
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Old 15-01-2018, 10:46   #7
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Re: Fresh Water Pump Not Producing Rated Output

I suggest that you check with the manufacturer for the expected flow at a 3'lift. Your lift will substantially reduce the flow rate but your numbers suggest some additional issue. if possible you can determine your flow at zero lift by measuring at a disconnected hose.
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Old 15-01-2018, 12:22   #8
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Re: Fresh Water Pump Not Producing Rated Output

Before fiddling with the pump, check the grid filters on your faucets. It worked for me.
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Old 15-01-2018, 16:15   #9
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Re: Fresh Water Pump Not Producing Rated Output

Quote:
Originally Posted by mboussem View Post
Before fiddling with the pump, check the grid filters on your faucets. It worked for me.
I did! One of the first things I checked. We do get sand in those filters... we apparently had a bad fill up at some point and a lot of sand got into the system.

I just found out that we have a three year warranty on the pump so I am going to check to see if we are still in warranty!
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Old 15-01-2018, 16:54   #10
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Re: Fresh Water Pump Not Producing Rated Output

Some faucet aerators have a flow restrictor in them (that cough can be poped out) I believe (if memory serves me) that a typical US kitchen faucet has a flow restrictor for about 1.5 gpm. Just a thought.
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Old 15-01-2018, 18:00   #11
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Re: Fresh Water Pump Not Producing Rated Output

You indicated this has occurred over time?
Does this low flow occur at the pump outlet?

1. You have back flushed the hose/pipe between the tank and the pump inlet.
2. When back flushing the pump suctions, you checked for water escaping from the hose/pipe. This would suggest a air leak on the suction side.
3. You have check and removed the inlet strainer. I am assuming you have reinstalled the strainer and checked the tightness of all hose clamps on the suction side of the pump.
4. You have visually inspected the internal parts of the pump.
1,2,3,4 had no positive effect.

Have you considered trying a new pump perhaps, a pump with a greater capacity?

I had a West Marine FW pump mysteriously failed slowly. I replaced it with it a different band of pump and seems to resolved all the problems.

My West Marine pump had a life of less than 3 years.
I have yet to experience the life of the current brand of FW pump. It is approaching 1 year.

One final thought, have you considered temporarily string a hose from the tank to the pump inlet to see its effect? When you replace the plumping from the tank to the pump (?) the internal diameter of the feed may be a smaller diameter. This will have an effect volume coming to the pump suction.

The funny part about being almost 75 years old is, the things I buy now will seldom wear out in my life time.
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Old 16-01-2018, 03:40   #12
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Re: Fresh Water Pump Not Producing Rated Output

Greetings and welcome aboard the CF, mboussem.
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