Priming a water pump

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Jan 13, 2005
While emptying the water tank on the old tub for sanitizing, the water pumps ran too long and completely emptied the tank. The result was that they would not prime. After a little coaxing, including cleaning out the filter attached to the pump and opening a faucet, one pump primed, but the other refused. We were hooked up to city water for the weekend, although we could have run on the one functional pump.

I was convinced it was a damaged diaphragm until some friends had a similar problem this weekend. Their issue turned out to be crud that had been in the bottom of their fresh water tank getting sucked into and blocking the water line from the tank to the pump. They merely blew out the line and were back in business.

I was going to do the same thing until someone mentioned that, when he had the same non-prime problem, he was unable to get the pumps to prime due to the back pressure from the accumulator. This morning I disconnected the output hose from the non-functional pump and voilla! It primed just fine and all is back to normal.

One lesson I learned was that, when disconnecting the line from the pump, the water that gushed out was quite warm - backflow from the water heater. Had I tried to do this when we got home yesterday and the water was still hot, I would have had a nasty surprise.
On of the pumps on my boat quit working this summer.  I just let it go using the other one, thinking I would get around to replacing it latter (not done yet).  I think I will try blowing out the line since my system has a lot of the crystallized crud.  Also, the last time I replaced a pump I had a difficult time getting it to prime.  Next time i will try the accumulator trick.
Just remember to do it when everything is cold. As it was, it startled me and I got out of the way as quickly as I could, given the tight quarters I was jammed into. Hope yours is easier to get to.

Since we had guests on board this weekend and the possibility of two showers running, we'd have had a problem with only one pump working if we weren't hooked up to city water.
The best way I have found to prime a water pump, as long as it's the fresh water tank, is to turn the pump on, then turn on a sink faucet , and suck on the faucet (slight vacuum).  If you cannot get your mouth under the open faucet remove your shower head from the hose and suck on it.

Do not use this method for black tank macerator pumps!!!  This is just like I learned when skiing..."Don't eat yellow snow."

LOL Jerry, I can see you now sucking on the shower hose. Do you wear the big boots when you do that?  :)

I don't ski, but I'll remember your "yellow snow" comment if I ever walk in the stuff and fall down  :-X

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