Originally Posted by intenseblu

schrader valve is the fuel pressure test port and its named so due to the internal mechanism that allows you to press in the valve and have a open line or let go of the valve and have it seal perfectly...

on the crossfire it is a standard 4AN fitting ... for those that are wondering, using a 1 dollar tool you can unscrew the inernal schrader valve and have a nice 4AN attachment point off the fuel rail to supply things like nitrous kits and extra injectors...