Water pump 'surging'

[PJHoffnet]

Recently my pot H2O pump has been 'surging' (quick run, quick shut off) when suppling sinks. When supplying flushing water to the heads, normal 'long run' and then stopping when use stops. There is a 'pressure tank' between the pump and the remainder of the pot water system.

Not sure if this is an indication of a pump that will fail soon, or if it's just being weird, or some pressure tank type of problem.

Any thoughts would be appreciated.

[team karst]

Pressure tank lost pressure and maybe bladder failure.

[markcouz]

also check the tap spout filters, they may block up if debris in the tank causing low flow rate which will also result in surging.

[Zanshin]

That sounds like a pressure tank issue. If you have a bicycle pump with a Schrader valve connector you can try pumping up the pressure on the tank. If that doesn't make a difference, then the internal rubberized membrane may be broken. Luckily, this is one boat part that isn't too expensive or complicated to replace.

[wrwakefield]

Optimum pressure for the pressure tank in a low pressure captive potable water system (what boats & RVs, etc. have- typically operating in a pressure range; e.g., pump on at lower pressure; pump off at higher pressure setpoint) is about 2 PSI BELOW the cut-in (start-up) pressure of the pump.

If you still have issues after setting the air pressure, the bladder in the pressure tank my have failed.

In hopes this is helpful.

Cheers, Bill

[Bowdrie]

An external pressure switch, (like a Square D,) with adjustable cut-in/cut-out makes life easier.
As for the accumulator tank, a few feet of hose and a gage with some fittings can make a remote reading pressure system that accommodates easy work with the air charge and pressure switch adjustments.
No, the gage isn't leaking, it's liquid filled for pulsation damping.

[PJHoffnet]

Thanks all ... transiting and on a ball/hook for the time being - will check the pressure tank at next marina stop in a few days and report back.

[PJHoffnet]

Sorry for delay in posting ... As Paul Harvey would say - here's the rest of the story.

Finished up our month long run down and back to Key West (with about two weeks in various ports to research Happy Hour(s) and good eats with the 'surging' water pump fulfilling our pot H2O needs with out further concerns. Yes, a bit unnerving/noising, but fully functional. While underway tried to increase pressure in the bladder, but it wouldn't hold pressure.

Got back and picked up a new accumulator (SHURFlo model 182-200 - same as the one being replaced). Some quick interest items. Old one was from August 2007 and made in the US. Replacement August 2022 and made in Mexico is identical as far as I can tell.

Disassembled the old one, bladder was 'intact' but was not seated properly. Reseated the bladder and the old unit holds pressure just fine now. I'll keep it as a ready spare.

Thanks to all who responded to the initial post.