I have a 34' which we just got a few months ago and when we took it for its first pump out yesterday nothing came out. The holding tank is full. But having studied the system i believethe PO may have been discharging directly ovrebaord. When i got the boat orginally i noticed that the sea **** thru hull discharge line was in an open position and immediately closed it. Now the really strange thing is that on the line going to the deck pump out fitting is a hand operated bellow type pump. I cannot firgure out what possible use this might be as it is after the Y valve. But when you try to pump out it immediately is suckde closed so i think thats why the vacum pump does not work. So the sysytem has not workde since new sanitation pipes were installed not that long ago i suspect. I cannot see any way anything gets past this bellows pump when the handel is eithre out of in , its internal valves would prevent it. And if i pump it all iwill do is put the holding tanks comtents out onto the deck !
any thoughts ?