richng
you are correct that i mean the tank is in the center range of the CG. YS or glow motors that are able to pull glow fuel from a distance. A vp-20 or Vp-30 is a pump used on glow motor 2 or 4 Strokes so that you can acheive the pump action with the glow fuel. This enable me to run all of my planes tank on the CG and not worring about starvation issues. here are a few pics of a pump and such.
Here is a link to read up on the vp pumps for now pumped glow motors:
http://www.perrypumps.com/prod02.htm
this pump is not requried for a gas engine or YS glow engine