I recently have been having issues with my "bilge" pump on my Amel 54. The pump is the original from TF Marine. I first noticed a problem that the motor sounded different, hard to describe exactly but I have tested it enough to know that the motor didn't sound the same, however pumping seemed normal. A few days later I noticed the pump was running for a very long time. After activation from the float switch, it began to pump, however once the water in the sump began to decrease, so did its pumping ability, so much so that it was unable to pump out the last bit of water to turn the switch off.
I rebuilt the pump with rebuild kit but had no luck so I gave it to the professionals for a rebuild. A few days later I am told they have the pump working and even send me a video (of the pump laying down on the ground, not upright) pumping plenty of water. Flapper valves, diaphragm, o-ring have all been replaced. Inside of the motor cleaned up. I also changed the suction hose that goes into the sump as it was getting old. There are two hose clamps on the suction side of the pump.
All this and still the same problem! The pump will prime just fine (hand over the outlet until the pump is full), then it will pump some of the water out of the bilge for a few seconds but then slow down to a crawl.
Is there some other source of a suction leak I may have missed? Is there anything else I could be missing?! Help!!