Holding Tank Pump - Failed/Not Priming?

[Jokani]

At the weekend my Jabsco 50890-1000 self-priming diaphragm waste pump stopped emptying the holding tank :-(

I disassembled it , but couldn't find anything obviously wrong, so just cleaned it up, and connected it to a 12v supply and appeared to work correctly, but if I put my hand over the inlet could't feel any suction, although strangely it did seem to blow air.

So that I could discount a blockage in the tank, I disconnected the pipe at that end and placed in a bucket of water, bit it wouldn't draw any water in.

The are expensive pumps, so I am reluctant to buy a replacement when I can't see what is wrong with this one or why it has suddenly failed.

Any ideas?

Also. macerator pumps are only slightly more expensive, would they prove more reliable?

 

[coopec]

Gary

I can't help you with the pump but could it be sucking air? Diaphragm OK?

I am building a yacht and while I buy the very best as far as bilge pumps and pressure pumps I tend to go for the el cheapo Chinese type macerator pumps for $A80 ( £45.)

I sometimes wonder whether I am doing the right thing buying cheap non critical items but I suppose time will tell.

Clive

 

[VicS]

At the weekend my Jabsco 50890-1000 self-priming diaphragm waste pump stopped emptying the holding tank :-(

I disassembled it , but couldn't find anything obviously wrong, so just cleaned it up, and connected it to a 12v supply and appeared to work correctly, but if I put my hand over the inlet could't feel any suction, although strangely it did seem to blow air.

So that I could discount a blockage in the tank, I disconnected the pipe at that end and placed in a bucket of water, bit it wouldn't draw any water in.

The are expensive pumps, so I am reluctant to buy a replacement when I can't see what is wrong with this one or why it has suddenly failed.

Any ideas?

Also. macerator pumps are only slightly more expensive, would they prove more reliable?

Its a pretty basic pump by the looks of it. A diaphragm and a couple of joker valves ?

If it the diaphragm is not damaged and is being operated by the motor that only leaves the valves one of which is probably not closing properly.

I'd replace both

 

[CLB]

I have that pump and mine also stopped pumping, although the motor was still running. It turned out that the plastic cam that turns the spinning motion of the motor to a pumping motion for the diaphragm had popped off on one end. Put it back on and its been fine ever since. When you say you took it apart, did you specifically look at this end of the pump?

 

[Jokani]

When you say you took it apart, did you specifically look at this end of the pump?

Hi, yes, I could see connecting rod was attached, when connected to 12v I could also see it rotating.

When I disassembled, there were thin circles of plastic paper in between the diaphragm pate and the diaphragm, and also between the connecting rod and the diaphragm, these are no on the parts explosion, do you remember seeing those/

 

[CLB]

Hi, yes, I could see connecting rod was attached, when connected to 12v I could also see it rotating.

When I disassembled, there were thin circles of plastic paper in between the diaphragm pate and the diaphragm, and also between the connecting rod and the diaphragm, these are no on the parts explosion, do you remember seeing those/

The issue with mine was that the crank (part J in the diagram above) had come off. I don't think I went further into the diaphragm part of the pump as this solved the problem. I had a full holding tank at the time, and my pump is connected directly to the bottom of the tank, so I was keen to look at all the 'dry' parts first :disgust: