Average Joe said:
On the freshwater pump there is a screen-type filter on the inlet side that gets clogged up with algae, etc. Unscrew it, clean the filter and replace it. Don't know about the saltwater unit.
No screen in the oem install.
First find the seacock and make sure it is open (level in line with the seacock. Make sure the seacock works ( level moves from on to off and visa versa before any of the next steps! With seacock open and assuming washdown still doesn't work, undo the feed (input from seacock) to the pump. Water should flow. Be ready to close the sea cock if necessary to stop water. If no flow, strainer may be clogged, seacock may be broken or hose may be clogged.
Next, connect water input hose to pump and then remove the output hose. Water may or may not flow out of the pump depending on particular washdown pump. If no flow, power up pump and see if water flows. If so, reconnect output hose and see where the water is being blocked ( bad hose or fitting, unusual though).
If no flow and pump makes noise, it is bad probably a sheared impeller or a damaged impeller.
The setup is pretty straightforward and the problem should be obvious.