Water Pump Bursts

justsomeguy · Feb 17, 2015

Joe Mullee said:
Over the past season I've been having a problem with the water faucets that wasn't there the first thirteen years I owned the boat. What happens is when I turn on the faucet the water initially comes out with normal pressure , no problem. But then after maybe 5-6 seconds of normal operation the water stops for a second or two and then BLASTS out spewing intermitantly for several seconds. It then goes normal again only to repeat the process. It blasts so hard that it will knock whatever is in my hand right out into the sink.

Anyone have any ideas on why this is happening? The pump seems to work fine.

Another issue is that for some reason when I fill the aft tank which sits higher than the forward tank the water from the aft tank will fill the forward tank. Somehow through gravity I assume the water is getting into the lower seated tank. Could this be due to a faulty switch valve that is used to switch between the two tanks?

Thanks for any help.

Joe Mullee
1983 Hunter 34

As to your first issue, you might have a accumulator that needs attention. It's a pressure-regulating vessel located between the pump and the spigot. Looks like a small barrel with a Schraeder valve on it, usually.

Don S/V ILLusion · Feb 17, 2015

Without guessing as to the cause, your desc sounds like air is getting into the piping. Last time you checked all connections?

justsomeguy · Feb 17, 2015

Joe Mullee said:
Thanks justsomeguy. There's no accumulator. Just the hot water tank between the pump and the spigots.

Then Don's guess is more likely. You didn't mention the hot water tank in the OP.

No problem with cold?

Don S/V ILLusion · Feb 17, 2015

We could spend more time guessing about where air is getting into the system...or

Stu Jackson · Feb 17, 2015

Joe, generally with two tanks, you only want to use one at a time. Especially if the higher one feeds into the lower one. You keep talking about a switch, but in plumbing they're called valves.

Do you have two valves into a header or do you have two pipes one from each tank going to a single selector valve which then feeds to the pump?

I have the former, and every time I forget to turn one of the two valves off this happens to me.

Stu Jackson · Feb 17, 2015

OK, Joe, now we have a good starting point. As I mentioned earlier, if that valve is leaking, it could mean that both tanks are connected at the same time. On my boat, if that happens and one (the higher) tank is empty and the lower tank isn't completely full, that happens to me, so I always run on only one tank valve open at a time. In your case, the first thing I'd do is remove and test that valve. Good luck.

Allan12210 · Feb 17, 2015

Joe Mullee said:
Stu, thats what I'm thinking too. Also will check the lines and connections for leaks as Don suggested.

Thanks to everyone.

If you still use the original selector valve, it is not possible in normal operation for the aft tank to drain into the forward one. Its basically a three way valve, so it can bring water from one or the other tanks to the pump or it is off completely. You might be able to use this to your advantage as I did once. After filling both tanks, see if there is a difference in the water flow depending on which tank is selected. In my case I found the settee tank fitting was loose as that's when the flow became erratic. If it happens with both tanks, then check the fittings at the valve on the pump draw tube, the screen filter and the pump inlet. Also check the packing nut on the valve itself.That may need a little tightening. The valve is easy to disassemble and rebuild if necessary. It may need a new o-ring available anywhere. They get flat after a while and the pump can suck air in along the stem.

Good luck.

Stu Jackson · Feb 17, 2015

Allan12210 said:
Also check the packing nut on the valve itself.That may need a little tightening. The valve is easy to disassemble and rebuild if necessary. It may need a new o-ring available anywhere. They get flat after a while and the pump can suck air in along the stem.

Joe, Alan's right about the O rings, if it's a plastic valve. One of my two valves started leaking, I replaced it with a metal valve, then took it apart, found O rings at the local ACE Hardware store (my favorite marine store!), and the valve is fixed! Evntually I'll put it back...but the metal one works just fine. I should have saved the $$ on the valve and just did the O rings, but backup, backup, backup never hurts.

Blitz · Feb 18, 2015

Also, clean out each of the aeraters screens on all of the faucets. Sometimes they clog with fine debris and do crazy things like build up presure, then spew out when passing fine debris.

kloudie1 · Feb 18, 2015

Had the same problem, Joe. I found the three-way selector valve had failed and was allowing air into the system from the empty aft tank. I pulled the valve and found that the coil spring inside had corroded and broken. Some bits of it had scored the plug that directs flow in the valve. I found a correct spring at Ace Hardware and a new o-ring for the shaft seal. I lapped out the plug so it correctly sealed again and it works as new again. The valve is common and can be purchased on this site or you can eliminate it and install two separate small PVC ball valves and a tee to better isolate the tanks.

EDIT: attached shot shows valve with top unscrewed and plug removed. Note the drool/corrosion on the mounting plate.. a sure sign that the o-ring is leaking a little.

Claude L.-Auger · Feb 18, 2015

Hi Joe,

Had the same problem a couple of years ago. Found out WM had those 3-way valve in stock for less than $15. So I did not mess with trying to fix, I just replaced. Pix may not be exact same 3-way valve but you get the point.

Ron20324 · Feb 19, 2015

Joe Mullee said:
...Can someone give me the size valve I need to purchase....

Tough call, Joe. Obviously it would depend on hose sizes (probably 1/2), but remember the valves pictured in post 16 still need 3 hose barbs.

Water Pump Bursts

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