It essentially has a seat and a bell shaped piece that closes and opens over the gas flow. The vacuum that is attached to it changes the point at which it will allow more or less gas past this seat and bell, like a seat and needle in a carberater, dependent upon vacuum. It allows more gas with more vacuum.
This is on the return line of the fuel system after the injectors.
Tuesday, November 13th, 2012 AT 6:10 PM