Bilge Pump Problem

[Petronella]

Hi All

New boat. A bit of brackish water coming into the deep bilge.

I can empty it by switching the pump to 'Manual'. However if I let the 'Automatic' function kick in it runs and runs until I lift the pump out of the water. AND it does not pump the water out! The float switch seems OK. It is, of course, very hard to get to!

Any ideas?

Thanks.
John

 

[RupertW]

I'm afraid it's a check it and see. The way I've done it is first to watch the float switch as water goes up and down and see whether it physically appears to rise and fall as expected without debris or objects stopping it, and also check that the pump goes on and off exactly when you observe the switch rising and falling. If both of those work then I'd suspect a blockage in the filter or pipe, and if not then it's bypassing the float switch to check the pump work (and I think you've virtually done that by manual, but worth a double check), then checking the resistance of the float switch as it rises and falls.

Hopefully one of your early checks will isolate the problem but if not then it's just step by dull step until the fault is obvious.

 

[Pump-Out]

Hi All

New boat. A bit of brackish water coming into the deep bilge.

I can empty it by switching the pump to 'Manual'. However if I let the 'Automatic' function kick in it runs and runs until I lift the pump out of the water. AND it does not pump the water out! The float switch seems OK. It is, of course, very hard to get to!

Any ideas?

Thanks.
John

If the bilge empties on manual then it can't be a blocked outlet.
The not switching off suggests the float switch needs replacing. However the fact that the water remains in the hull suggests, and this would not be the first time I have seen this - you have two bilge pumps!

 

[coopec]

"The float switch seems OK. It is, of course, very hard to get to!"

Within days I will install my three bilge pumps. I have deep bilges so I have mounted my bilge pumps/switches on to acrylic/plastic/nylon(?) planks and lowered them into the bilges. They are secured into place 6 inches (15cm) from the bottom of the bilge by a bolt and wing nut so that they are not constantly submerged in bilge water.(I figure the expensive pumps will last longer that way) I then have small/ cheap (450 lph) manually controlled bilge pumps to lower the water level to almost zero.

By the sounds of it the float switch is integral with the pump unit? Maybe you have to remove the bilge pump and test it in a bucket of water?

Clive

 

[prv]

Leaving aside for the moment the question of how long it runs, I cannot see how a pump can empty the bilge when run manually but not when it runs on auto. Unless possibly (and assuming a centrifugal pump) it’s wired so that it runs backwards in auto mode? That seems to require quite an elaborate wiring cockup.

Otherwise I wonder whether, in your deep bilge, you’ve failed to notice that the two modes actually activate two separate pumps?

Pete

 

[Graham_Wright]

Another possibility is that run back is refilling the bilge. If the pump is deep, there is a fair lift to the exhaust point. My bilge pumps all exit via a manifold to the transom. With a centrifugal pump, it does not matter if it runs dry so can run beyond the level dictated by the float switch. But that column of water in the exhaust pipe will run back when the pump is switched off and cause the system to cycle.

The solutions seem to be a non return valve, an electric valve that opens when the pump runs or a vane type pump that is inherently non return.

Non return valves tend to become fouled and leak back. The electric valves I have found restrict the flow. Vane pumps (e.g. Jabsco) don't like running dry.

Take your pick!

 

[prv]

Another possibility is that run back is refilling the bilge.

That could maybe explain the "continuous" running (though it wouldn't really be continuous but pulsing) but I don't think it tallies with the statement that the manual mode can empty the bilge but the auto doesn't. If the amount that runs back is enough for him to consider the bilge "not empty", then it will also apply when he switches off the manual run.

Pete

 

[Buck Turgidson]

If the pump works on manual then the pump is fine. Backfilling would occur in either mode if it was the problem.
I have a feeling like others that the Auto position may be a different pump.

 

[Petronella]

If the pump works on manual then the pump is fine. Backfilling would occur in either mode if it was the problem.
I have a feeling like others that the Auto position may be a different pump.

Thanks for all the replies. A new pump is on the shopping list. I will fit it and then investigate the problem with the old one as I could use a spare anyhow. Interestingly it has also stopped pumping water when on manual now. Maybe that was a red herring (which would make more sense) and it's just that sometimes it works and sometimes it doesn't. Investigations continue.

There is only one pump. I can hear it whirring in Auto or Manual.

I will start another thread inquiring as to the best Automatic Bilge Pump.