Hi all,
I noticed today that my auto bilge pump although activating when I lift the float switch is not actually pumping water out into the cockpit.
If I remove the pipe connected to the pump itself and activate the switch it will pump water into the bilge but when I reconnect the pipe although it still sounds like it's working nothing comes out of the other end. I have taken both ends of the pipe off and blown down it and there does not seem to any blockage at all.
So I can only think that the pump is not now strong enough to pump the water up through the pipe? Which means a new pump unless anyone has any other ideas?
One other thing, the pump has what looks like a small breather on top with a very small plastic ball under it, this was blocked and I did clean it but still not sure what it does exactly?
cheers

The small tube with the plastic ball is an air bleed to discharge air from between the pump and check valve. The plastic ball is a float valve that seals the tube once the air has been discharged. It's basically to ensure that the impeller and pump housing are flooded.
If you have an airlock between the pump impeller and a check valve the pump may not prime.

Cockpit said..



As can be seen it is pumping water but doesn't seem to have much pressure even though it looks ok in the photo.
The hole at top is where the plastic ball goes along with a small cap with holes in it. I did try it both with and without the ball and cap with the same result, it appears to be working but no water out the other end of the pipe and the pipe run has been the same for years so I'm not sure that altering it will help?

Check voltage at pump, if a corroded connection it can still run but not at full speed or power.

Haven't pulled one like yours apart so this may not apply but if the voltage is alright I'd check the impeller housing for blockage or a broken blade on impeller.

I had that situation more than once with those red and blue bilge pumps. Both times It was a broken coupling between the motor shaft and the impeller. With no load it would appear to pump OK because the tiny friction between the motor shaft and broken plastic where it was meant to couple onto the impeller could get the impeller going. As soon as the output of the pump was blocked a little (with finger) the impeller wouldnt spin and water output would stop. I think the theory about the wire being high resistance (corroded) could be right too.