WaterPump Runs but Doesn't Pump

[Dreamnair]

Every year at this time we run into a problem getting our water pump to pump. It runs, and we even try to prime it by adding water through a bypass, but it just doesn't want to move water.

The only time we use the pump is to winterize and the water tank is empty most of the time. Could this have something to do with it?

In the past we've usually gotten the pump to work, but never know what we did to make it happen. When it pumps it pumps fine; it's getting it started that is always the problem.

Any ideas out there?

[txtwin]

On my AS, I have to open a faucet to get mine to prime and pump. Once its pumping, no issues and the pump shuts off when I close the faucet. My boat is very different, its pump picks up immediately, and doesn't need a faucet opened to prime.

Not sure this helps. Good Luck.

[Ted S.]

Try opening the faucets, it's probably air.

[Dreamnair]

I've been opening faucets. Trying them open just a little and then wide open. No real difference.

[Ted S.]

I had the same problem and that worked for me. Did you try the outdoor shower?

[HowieE]

The pump may have lost its prime. Put water in the fresh water tank, a few gallons. On the input side of the pump there may be a filter. Remove the line from the fresh water tank to the filter and put a piece tubing to it. Pore water into that tube till you see water in the filter bowl. Reconnect the fresh water supply line and try the pump with at least one fauset open.

Sitting for a long time the water in the supply line may flow back to the tank causeing the pump to lose the prime.

[Dreamnair]

[Sitting for a long time the water in the supply line may flow back to the tank causeing the pump to lose the prime.]

I think you're right, but I'm thinking the reason it loses prime is that the seal dries up over the summer. Then when I start working with the pump I get a little water into it and the seal swells up and does what it's supposed to... pump.

Will try again in the morning to see if the theory holds up.

[Dreamnair]

For a bit of closure, we (actually, my friendly RV repair guy) finally got the pump going again and it works just like it's supposed to. It took him an hour or so to make it happen, but the diagnosis was just as I thought... dry seals. He claims that RV antifreeze actually pulls moisture out of the seals over the winter. Then if I go all summer without using it the seals are shriveled up like raisins (or maybe old donuts).

In any event, de-winterizing will now include partial filling of the water tank and occasional use of the pump just to keep it happy.

[Al and Missy]

The water pump, with good valves, should pull water regardless of if there is air, but not an air leak, in the input line. Centrifugal pumps must be primed. Diaphragm pumps, like the ones in our trailers, are self-priming as long as the valves work properly. If you have to take unusual measures to get your pump to work, you will ultimately have a complete failure, it's just a matter of time.

Al

[BessieB]

So basically, my pump has failed. Correct? It worked all summer until I left for my trip.

[HowieE]

Originally Posted by BessieB

So basically, my pump has failed. Correct? It worked all summer until I left for my trip.

As a new poster to this tread i am not sure what would cause you to come to that.

Prime the pump.
If there is or was air in the line it will not pick up a prime from the tank. As for eventual failure from what ever reasoning is noted above I have had to prime my pump every time I pump antifreeze while winterizing. The pump will not draw directly from a gallon of antifreeze at floor level and over the sill of the closet. I have to lift the gallon. That has been the case for the last 20 years so I don't think it is an indication of eventual pump failure