Where is the water pump for the sink on 23' gulfstream

On my '89, it is under the port pedestal seat. Pull out the tackle storage box, and the pump is next to the fresh water tank. You will have to unbolt a couple 2X4s to get your head down in there.
 
I have a 2000 Gulfstream and the freshwater pump is located under the port side helm chair. You will need to remove the two tackle drawers in order to get access to it.