Originally Posted by
Hobbsy
Any time you use mechanical devices to move something through an enclosed space it is a pump. In this case the bottom line is that this crankcase pump moves fuel. That's about as pumpy as you can get. Semantics won't change the facts.
The disc doesn't move anything. It opens a port which allows the crankcase pressure through to the inlet. That's why it is a valve and not a pump.