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Fuel Filler Cap: Description and Operation
FUEL TANK FILLER TUBE CAPThe loss of any fuel or vapor out of filler neck is prevented by the use of a pressure-vacuum fuel tank filler tube 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 fuel filler tube caps is between 0.97 and 5.0 kPa (0.14 and 0.72 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 fuel tank filler tube cap before servicing any fuel system component. This is done to help relieve tank pressure.