Once known as Hartley18
Join Date: Aug 2007
Location: Melbourne, Australia
Thanked 65 Times in 65 Posts
Rep Power: 10
Diaphragm pumps have rubber flappers on the inlet and outlet side of the round bit (called check valves).
If you can't find any obvious problems with the hoses, it's very possible some rubbish has got though your filter and jammed under one of these - it doesn't take much. You'll have to take the diaphragm off to check it (just undo the hose clamp), but make sure you put it back nice and tight or it won't seal.
"Honestly, I don't know why seamen persist in getting wrecked in some of the outlandish places they do, when they can do it in a nice place like Fiji." -- John Caldwell, "Desperate Voyage"