Freshwater pump not turning off

[stormalong]

Originally Posted by Alita49DS

If it is a Jabsco pump the good news is that the seal service kit is about a quarter the price of a new pump. Both extortionate.

The other good news is that servicing the thing is not difficult as it is a primitive device.

However, the bad news is that the instructions that come with the kit are a disgrace. Jabsco UK agree but say not us, the Americans.

So, before you take the thing apart grab your mobile phone (who bothers with a camera these days?).

1. Photograph the base. In particular one of the protruding threads.
2. Once you have separated the pump from the motor and lifted up the diaphragm be careful not the dislodge the innards. Photograph the two circular valves making sure you have a reference point.

Why? In relation to the above:

1. Normally you would tighten a seal to make it waterproof. Right? Wrong. If you over tighten the four long screws the thing will not only leak but make a racket as the screws hit the bulkhead. So count the threads that went through before.
2. The inlet and outlet valves are the same and there is no way to tell which way up they go unless you have a record.

The primitive beast only has a flow rate of 10 to 13 litres a minute. If you are lucky.

I wonder who designed the thing - and when.

Sounds like you are talking about the Jabsco 36950. It was designed about the same time as the Perkins 4-108. Both good but primitive by today's standards. I use one and have a rebuilt spare ready to go when it needs servicing.

One thing I have discovered about pressure switches is that the switch is under rated for the electrical load. The contacts arc and fail. To solve this I rewired to have the pressure switch activate a relay to power the motor. I use a 20 amp automotive headlight relay. They are available at any auto supply shop and fit into a socket. Have not had a pressure switch fail since.

The slow pumping could have been an early sign of pressure switch failure. As the switch contacts get pitted the switch resistance goes up and the current available to the pump drops.

[Smokeys Kitchen]

We started having issues with our old Jabsco pump/accumulator system shortly before we moved aboard our boat. It would not shut off and also developed a nagging leak under the sink. The boat had been little used in the prior year or so; mostly sitting.

As opposed to CarlF, I went with a ShurFlo Aqua King II demand pump. The installation holes mated up to the old Jabsco pump so it was easy to install. It varies the pumping speed to meet demand (up to max of 3 gpm) and there is no accumulator tank. As an added benefit, it is not damaged if it runs dry (ShurFlo's marketing), although I have not tested that extensively. We have been using it for @ 18 months now and really like it, and have not had any issues so far. I think it ran @ $85 from Fisheries at the time.

I do agree with CarlF on making sure the electrical connections are well done and not scrimping on the connectors or tools. It is not 'wet' under my sink - where the pump is located - but the humidity is high and the connections need to be solid and covered (heat shrink).

[ThresherMan]

I had the same problem last year. The fix turned out to be emptying the pressure/accumulator tank and lines downstream of the pump and blowing it out entirely with an air pump. A burst of the pump to clear any bubbles in the pump and reattaching all. The pump had to be replaced because the PO had installed the pump upside down, with the motor below the diaphram, which allowed leakage into the motor and rusting it shut.

[Dave22q]

This repair is about as simple as it gets. If the pump runs continuously you either have a leak, the water tank has run dry or your pump pressure sensor is bad.
First rule out leaks by checking your tank. Modern pumps will run dry for a long time attempting to self prime. If no leak, replace the pump rather than messing with it. Generally 2 hose connections, 2 wire connections and a few screws to hold it in place. Many could do the whole thing in under an hour at a cost of $50 to 150 depending on pump size. I would not worry about air bubbles as most pumps are self priming. Even if located in a dry place I would heat shrink the electrical connections. Good luck!

[lsearite]

My pump went out last year on my 2008 Meridian Sedan. I am now working on the 5th replacement from Jabsco in 14 months. It is their FLO 5.0 model 42755-0092. I have run across 2 other boaters having the same problem with this pump. The company has been good about responding and replacing but every time I have to send one back it cost me $38 dollars and change.

Just my experience. Good luck.
Louise Seawright

[Mike Banks]

Check that your intake filter is not obstructed, (you said the water flow was down) first.

These pumps are only a couple of hundred dollars new--so it may be time to replace it--