mystery part in bilge pump

[Sailorman Ed]

I took apart my Jabsco 36680 Series Diaphragm Bilge Pump tonight because it was not pumping correctly, The valves look fine and all the gasketing and diaphragm look good. I did find this almost rigid molded part under the valves and I cannot figure out what the purpose is. there was some water in the lower chamber (not where the valves are). I will clean everything and then reassemble and see if it works any better.

[HopCar]

It's called a pulsation dampener. It is Jabsco part number 44127-1000.
Water should not get below it. If water is getting below it, air can get above it and reduce pumping capacity. If it has hardened, the pump can get pretty noisy. It also functions as the bottom gasket on that pump. It'll probably still run but you should replace it.
Here is a link to the parts list and instructions. http://www.xylemflowcontrol.com/file...43000-0534.pdf