Shurflo Water Pump

[sailcomp]

We bought our 2018 Tayana 48 last November. It came with one 12v Shurflo water pump which someone had done some weird rewiring to. The flow at the galley sink was medium-low. In any case it stopped working shortly and we discovered by tapping on it that it was the pressure switch. We have had another boat for 20+ years that also came with a Shurflo pump and I'm sure over the years we replaced it once but that might be it, so we were fine with installing another Shurflo. Now the thing is starting to act up-- last night it kept "running" with no water selected. We looked in the bilge under every floor we could and NO water anywhere. Anybody got any ideas? And while we're at it, can I get some recommendations for a different water pump?

[a64pilot]

Depends on how much money your willing to spend, most of us get by with the less expensive diaphragm pumps, mine is a 5.5 GPM pump, which means of course that it pulls quite a bit of power, the pressure switch activates a micro switch and all power goes through that little switch, so after I believe the second failure, I figured out that the switch could not handle those kind of amps over and over, so I replaced the switch and installed a relay to switch the power, the micro switch just activates the relay, the relay carries the current and all has been well since.

It’s my understanding like many things to get a very good pump, cost a great deal of money. I will likely go that route after I wear my current pump and spare out.

[wiekeith]

I had a similar experience with a replacement Sureflow pump. The original pump (about 12 years old) had an adjustment screw that allowed you to set the pressure at which the pump would turn off when no water was flowing, which was useful. However, the replacement pump had two adjusting screws. The second was, as I understood it, to set a bypass pressure, so if the desired pressure set by the first adjustment screw was reached when water was flowing, it would relieve some of the pressure by allowing some of the pumped water back into the inlet chamber, hence preventing the pump from cycling when in use.

The instructions warned that if the setting of the bypass was incorrect then the pump could run continuously without any water actually being pumped to the faucet.

However, I could not get the settings correct. The pump would sometimes not work until it was given a knock, and other times would keep running with no water flowing – as you’ve reported.

My pump is very difficult to access, so after many frustrating attempts at setting it up I eventually cut my losses and fitted a whale pump, which has worked perfectly since.

[sailcomp]

Thanks. On our way to buy a new pump. Not a shurflo!

[wingssail]

Originally Posted by sailcomp

We bought our 2018 Tayana 48 last November. It came with one 12v Shurflo water pump which someone had done some weird rewiring to. The flow at the galley sink was medium-low. In any case it stopped working shortly and we discovered by tapping on it that it was the pressure switch. We have had another boat for 20+ years that also came with a Shurflo pump and I'm sure over the years we replaced it once but that might be it, so we were fine with installing another Shurflo. Now the thing is starting to act up-- last night it kept "running" with no water selected. We looked in the bilge under every floor we could and NO water anywhere. Anybody got any ideas? And while we're at it, can I get some recommendations for a different water pump?

On our boat when the waterpump runs continuously and no water is produced at the tap we then check the screen filter which is in between the tanks and the pump. Periodically this filter fills with some calcium sediment (like corn flakes) from the inside of the tanks. This sediment can also clog the tank pick up. If you disconnect the inlet hose on your shurflow and suck on it with your mouth you will quickly find out if there as a blockage.

Our Par Max4 pumps (we have two) have been indestructible through many many years of heavy liveaboard usage. We've always carried a spare. Now there is a new model. We would buy Par pumps again.

[kmacdonald]

Use a strainer before the pump. Even small debris will cause the pump to fail. You can take apart the pump and remove the debris and it will work fine again. Really small debris that you wouldn't think would hurt it will make it fail.

[Lepke]

The reason diaphragm pumps (with the pressure switch on the end) fail is the switch is usually too small for the amps passing thru. Most are AC rated for 15 amps @ 240V. On 12v the contacts can't handle the amps, become burnt and pitted. Then the switch fails or supplies lower voltage to the motor that eventually fails. When I use that type of pump, I use an external pressure switch. Switch shown is typical diaphragm pump switch, found in many house appliances, less than $1 on eBay.

[sailcomp]

Thank you all. I enjoyed reading the responses and super grateful to have found this forum. Glad the Par-Max pump was recommended as that is what we just bought! Took apart the old Shurflo and along with some of your descriptions
we learned a few things about pumps . I'm glad the pump failed in the dock. There was an interesting story from the delivery captain about running out of water bringing the boat to SF Bay from Japan. Apparently they ran out of water when one of the crew left the spigot open in the head after brushing his teeth. That always sounded unlikely to me and we hoped to get more details but never did. I just wonder if it had anything to do with the pump, which had some really weird rewiring when we bought it. Oh yes, apparently the captain was able to get a ship to drop jerry cans of water nearby. What a pickle!!