Fuel Vapor Emission Control System

As a part of the fuel system, all vehicles are equipped with fuel vapor evaporative emission control systems to meet federal requirements in effect at the time of production.

The basic fuel tank venting system is typical for all vehicles.

The fuel evaporative emission system allows for controlled release of fuel tank pressure through a fuel vapor canister (9D653) . Under normal operating conditions, this system will allow sufficient venting to prevent a build-up of internal fuel tank pressure.

Some operating conditions may cause temporary build-up of internal fuel tank pressure. Some of these conditions are:

• On warm or hot days, parking the vehicle after filling the fuel tank (9002) , the fuel is cool from underground storage and vaporizes rapidly when warmed.
• Parking after driving over rough roads, washboard, or other harsh surfaces, after filling the fuel tank . Agitation of fuel increases vaporization.
• Parking after driving long distances in high temperature conditions.
• Climbing long grades, especially while towing a trailer, or while fully loaded.

A normally functioning fuel tank evaporative emission system will relieve the pressure buildup.

No service is required if these conditions caused the customer concern.

A blocked fuel tank evaporative emission system can cause abnormal fuel tank pressure and must be serviced. Refer to Inspection and Verification as outlined.