Town & Country Van 2WD V6-230 3.8L VIN L SMFI (1997)
Fuel Filler Cap: Description and Operation
Fig 3 Pressure Vacuum Filler Cap
A pressure-vacuum relief cap seals the fuel tank (Fig. 3).
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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.
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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.
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Removing the cap breaks the seal and relieves fuel tank pressure.
The filler cap is also a pressure/vacuum relief valve, which opens whenever pressure in the tank gets either too low or too high.
Filler cap venting pressures:
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Pressure above 10.9 to 13.45 kPa (1.58 to 1.95 psi)
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Pressure below 0.97 and 2.0 kPa (0.14 and 0.29 psi)
Only filler caps with these specifications may be used as replacements.
WARNING: Remove filler cap to relieve tank pressure before removing or repairing fuel system components.
