Holding Tank - how to pump?

[Sea Shift]

I have a 265 Express I am trying to pump. I tried to pump out my holding tank the other day with a dock side pumpout. It keept pumping but didn't seem like any liquid was comming out. Is there a valve on the boat side that needs to be opened? It seemed like there was a squeeking noise I could hear in the head. thanks for the help.

 

[Tucker]

I've always had a hard time pumping holding tanks. I don't use the clamps on the vaccum nozzel. I hold the nozzel in the hole letting some air vent in.

 

[wspitler]

There is a vent line, much like the older fuel tank vents on the side of the hull that allows air to enter the tank as you suck out the contents. Check to make sure it hasn't been clogged by dirt dobbers or other insects. Mine was clogged. It's a pretty small orifice.