EVAP System Components

1999 Chevrolet Express 1/2 Ton Van V6-4.3L VIN WSECTION EVAP System Components

Component Location:





The purpose of the Evaporative Emission ([1][2]EVAP) control system is to prevent the fuel vapors from escaping into the atmosphere. The EVAP transfers the fuel vapor from the sealed fuel tank to an activated carbon (charcoal) storage device (EVAP canister). The EVAP canister stores the vapors until the engine is able to use the extra fuel vapor.

When the engine is able to use the extra fuel vapor, the intake air flow purges the fuel vapor from the carbon element, and then the normal combustion process consumes the fuel vapor.

The system is designed to detect the evaporative fuel system leaks as small as 0.040 of an inch between the fuel filler cap and the purge solenoid. The system can test the evaporative system integrity by applying a vacuum to the fuel tank in order to create a small vacuum. The VCM then used the fuel tank pressure sensor to determine system integrity.
RENDER: 1.0x

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • You smell fuel, burning insulation, or see smoke.
  • Brakes feel soft, pull hard to one side, or make grinding noises.
  • The engine overheats, stalls repeatedly, or misfires under load.
  • You are missing required tools, torque specs, or safe lifting equipment.
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