Neon L4-2.0L VIN C (1998)
Fuel Filler Cap: Description and Operation
Fig. 4 Pressure Vacuum Filler Cap
WARNING: Remove fuel filler tube cap to relieve tank pressure before removing or repairing fuel system components.
PURPOSE
A pressure-vacuum relief cap seals the fuel tank (Fig. 4).
The loss of any fuel or vapor out of the filler tube neck is prevented by the use of a safety filler cap.
OPERATION
Tightening the cap on the fuel filler tube forms a seal between them.
The relief valves in the cap are a safety feature. They prevent possible excessive pressure or vacuum in the tank. Excessive fuel tank pressure
could be caused by a malfunction in the system or damage to the vent lines.
The seal between the cap and filler tube breaks when the cap is removed. Breaking the seal relieves fuel tank pressure.
Pressure Release
The cap releases only under significant pressure 10.9 to 13.45 kPa (1.58 to 1.95 psi).
Vacuum Release
The vacuum release for all gas caps is between 0.97 and 2.0 kPa (0.14 and 0.29 psi).
Replacement
If the filler cap needs replacement, only use an original equipment or equivalent unit.
