Prizm L4-108 1.8L DOHC VIN 8 MFI (1998)
Fuel Filler Cap: Description and Operation
Fuel Filler Cap
Notice: It a fuel tank filler pipe cap requires replacement, use only a fuel tank filler pipe cap with the same features. Failure to use the correct fuel tank
filler pipe cap can result in a serious malfunction of the fuel system.
The fuel filler cap is a pressure-vacuum type. A built-in torque limiting device on the cap prevents overtightening and also eliminates the escape of fuel
vapors. To install, turn the cap clockwise until a clicking noise is heard. This indicates that the fuel filler cap gasket (1) is fully seated.
A vacuum relief valve (2) is incorporated into the fuel filler cap. If the pressure in the fuel tank becomes negative (vacuum), the relief valve opens to
relieve the pressure created within the fuel tank. Only when the vacuum becomes excessive within the tank does this occur. Vacuum pressure is also
vented through the tank pressure control valve which is located on the top of the fuel tank.
A pressure relief valve is also located in the fuel filler cap. The pressure of the fuel vapor within the tank should exceed that for which the fuel system is
designed, the pressure relief valve opens, and the excess pressure is vented to the atmosphere.
