Fuel Filler Cap: Description and Operation
PRESSURE-VACUUM FILLER CAPThe loss of any fuel or vapor out of the filler neck is prevented by the use of a safety filler cap. The cap will release pressure only under significant pressure of 10.9 to 13.45 kPa (1.58 to 1.95 psi). The vacuum release for all gas caps is between 0.97 and 2.0 kPa (0.14 and 0.29 psi). The cap must be replaced by a similar unit if replacement is necessary.
WARNING: REMOVE FILLER CAP TO RELIEVE TANK PRESSURE BEFORE REMOVING OR REPAIRING FUEL SYSTEM COMPONENTS.