Freshwater pump not building pressure

[nuru05]

I have a brand new fresh water pump I just installed last month that doesn’t seem to be working. It never shuts off but the faucets in the boat have very little pressure. They just seem to dribble at about 20% of normal and then stop for a few seconds and sputter and then dribble again. I went to the pump and pulled the fitting off by it and I am able to easily stop the pressure with my finger and it still never builds to a point that it even shuts off. Did my new pump already fail?

[tkeithlu]

Given that you are not flooding the boat, and there is water in your tank, it sounds as though pressurized water is leaking back to the vacuum side of the pump. The most likely cause would be a piece of debris caught in one of the two duck bill valves. A torn diaphram is a possibility, but less likely given a new pump. Oooops. One othe possibility: an air leak on the vacuum side, probably where you connected the pump.

In any case, it sounds like time to go back over the installation. You could start by plumbing the pump into a new source of water to see if it then pumps. Then pull the duckbill valves to see if one is being held open. Then actually get into the pump and look for a tear.

Good luck with it.

[Shrew]

It sounds like the pump isn't completely priming. I had a problem very similar and it turned out to be the pre-filter to the pump was sucking air.

[Manateeman]

Make of pump. Electrical connections perfect? Run a jumper straight to a full battery. Obstruction in water feed? Accumulator tank?
Try the pump out of boat. Will full water flow through your system...say with dock hose or another ? Try backfeeding the supply line to the pump. Maybe something stuck in line or floating in tank.
Some pumps don’t like air in the feed. Loose hose?
That’s all we got. Need another gallon of coffee.
The manatee crew.

[valhalla360]

If it's brand new, I would test with a short section of hose pulling from a bucket of water to make sure the pump is working properly.

If it fails, I wouldn't bother tearing it apart. Take it bac and ask for a replacement. Now if it was a pump you've had for a while...I have pulled them apart with mixed success.

[Bowdrie]

You didn't indicate the type of boat, or the orientation of the pump in regard to the tank(s).
Does the pump have to lift the water from the tank? If so, there may be an air leak between tank and pump.
It takes only a very tiny air leak to ruin the flow.
Pumps are much better at pushing water than they are at sucking water.
Any mounting scheme that will get the pump below the tank will always lead to a better system and longer pump life.

[Tin Tin]

Installed a new Whale pressure pump the other day and the output was same as you describe. Turned out to be an air leak at the tank hose connector, double clamped it and all good.