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Re: Improved water pump w/Relay
Posted: February 22nd, 2023, 8:52 am
by KyleR
In my personal experience though, a freshwater pump failure has rarely been due to the pressure switch.
My Shurflo pump just died and it was due to the pressure switch. When I put a continuity meter across the switch it would only work about once every 20 times I pressed the switch. I sprayed it with DeoxIT D5 and mechanically agitated it (i.e. banged it a few times) and was able to get a few more days out of it waiting on the replacement to show up. Even then I had to go bang on the switch a couple of times to get it working during those few days.
But what my point is, as I was researching this, the recurring theme I found was that these pressure switches are the MAIN reason these pumps fail. Rarely was it ever due to a diaphragm/motor/etc.
With that said, I will acknowledge that the pump I just replaced was 21 years old - so I really can't complain!! Granted the boat wasn't used much before we bought it, so the actual run-time on the unit was much less. But I figure it was due for replacement so I'm not complaining!

Re: Improved water pump w/Relay
Posted: August 17th, 2025, 6:54 pm
by KyleR
As a followup since my last post approx 2.5yrs ago when I replaced the original pump with a Shurflo Aqua King II.....
Since that time I have had the pressure switch fail twice in that period. Maybe our pump cycles more than most since we live aboard full-time and are rarely in a marina, so we're never hooked up directly to shore water. For whatever reason, that little micro switch has been the culprit every time.
This time, I disassembled that switch and found serious evidence of charing and pitted contacts indicating that way too much current is being passed through that switch. Add to that the repeated cycles it experiences every time the pump turns on and off and it's no wonder it keeps failing.
Anyway, I installed another new micro switch but this time I added the relay as suggested in the original post. Everything seems to be working great, but only time will tell.
Kyle
Re: Improved water pump w/Relay
Posted: August 17th, 2025, 7:52 pm
by buster53
KyleR wrote:QR_BBPOST As a followup since my last post approx 2.5yrs ago when I replaced the original pump with a Shurflo Aqua King II.....
Since that time I have had the pressure switch fail twice in that period. Maybe our pump cycles more than most since we live aboard full-time and are rarely in a marina, so we're never hooked up directly to shore water. For whatever reason, that little micro switch has been the culprit every time.
This time, I disassembled that switch and found serious evidence of charing and pitted contacts indicating that way too much current is being passed through that switch. Add to that the repeated cycles it experiences every time the pump turns on and off and it's no wonder it keeps failing.
Anyway, I installed another new micro switch but this time I added the relay as suggested in the original post. Everything seems to be working great, but only time will tell.
Kyle
If you don’t already have one, consider adding an accumulator tank to your onboard water system. If will definitely cut down on the number of pump cycles, which should make it last longer.