Originally Posted by pizzaguy

No. You can't cycle the top with the tank low or empty.

You suck out all the fluid you can from the tank, then refill it.
Cycle the top a few times.
Then suck out the tank a second time and refill it.

That's about the best you can do. You will get 90% or more between the two evacuations. You can't get 100% because there is always a small amount in the lines.