generally, any valve or device located part way down the filler neck is to prevent stealing gasoline or prevent large objects from entering the neck. I'm assuming your talking about the little tin flapper that the gas nozzle pushes down as you insert it to fill your tank. any important part of the gas system would be in the tank itself or in the gas cap. I'm not a prius expert just sharing my general knowledge. Hope that helps.
The Prius was invented and developed by Toyota.
Toyota Prius was created in 1997.
Camry Prius C Prius V Volt
Toyota Prius v was created in 2011.
Hybrid cars: Toyota Prius Toyota Prius V Toyota Prius C Honda Insight Hyundai Sonata Hybrid
Bugs Bunny does drive a Toyota Prius.
The 2007 Toyota Prius has 16 valves.
The 2006 Toyota Prius has 16 valves.
The 2005 Toyota Prius has 16 valves.
The 2004 Toyota Prius has 16 valves.
A 2012 Toyota Prius exterior body width is 68.7"
The 2011 Toyota Prius has 16 valves.
The 2012 Toyota Prius has 16 valves.
The 2010 Toyota Prius has 16 valves.
The 2002 Toyota Prius has 16 valves.
The 2003 Toyota Prius has 16 valves.
The 2001 Toyota Prius has 16 valves.
The 2009 Toyota Prius has 16 valves.
The 2014 Toyota Prius has 16 valves.
The 2008 Toyota Prius has 16 valves.
The 2013 Toyota Prius has 16 valves.
The Prius is a Toyota.
Our 2009 Toyota Prius hold 13 gallons.
The 2001 Toyota Prius is a hybrid-powered vehicle.
The 2011 Toyota Prius is a hybrid-powered vehicle.