Home >> Ford >> 2004 >> Excursion 6.8 S, RWD >> Repair and Diagnosis (Single Page) >> Engine Mechanical >> Auxiliary Emission Control Systems >> Evaporative Emissions System - Excursion & F250-F550 Super Duty >> Diagnosis And Testing >> Evaporative Emissions >> Pinpoint Tests >> Pinpoint Test D: Hiss When Opening Fuel Cap