2500 4x2 Pickup V8-318 5.2L Magnum (1994)
Fuel Filler Cap: Description and Operation
Pressure-Vacuum Filler Cap
PRESSURE-VACUUM FILLER CAP
The loss of any fuel or vapor out of filler neck is prevented by the use of a pressure-vacuum filler cap. Relief valves inside cap will release only
under significant pressure of 6.58 to 8.44 kPa (1.95 to 2.5 psi). The vacuum release for all gas caps is between .97 and 2.0 kPa (.14 and .29 psi).
This cap must be replaced by a similar unit if replacement is necessary. This is in order for the system to remain effective.
CAUTION: Remove filler cap before removing or repairing fuel lines. This is done to help relieve tank pressure.
