These are part of the emission control system.  They allow the gas vapor
from the tank and fuel system to accumulate (in conjunction with the
charcoal canisters) until the engine is at operating temperature.  The
vapor is then purged while the engine is running above idle.

James

> Javier wrote:
>
> Today I was looking under my Westy�s front wheel and saw, on both
> sidesof the van a couple of plastic tanks that seems to contain
> gasoline coming back from the tank?
> What are these for?
>
> All info will be highly appreciated.
>
> Javier Zavala
> 84 German Westy
> 01 Prospector Hovercraft