I've got a big tanker that I've been trying and trying to use, but no matter what I do, every attempt to pump fluid out of the internal spaces fails hard; all flow completely stops. Here's what I've tried:

*Moving pumps around, trying from the top; trying from the bottom.
*Making sure there are plenty of gas relief ports
*Forcing gas in to try to pressurize it
*Deleting all physics flooders

Nothing has worked. I'm stumped. Wtf is wrong with this thing?