Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Fuel Evaporation System: Description
The purpose of the Evaporation Control System is to prevent gasoline vapors (hydrocarbons) from the fuel tank, carburetor and throttle body, from entering the atmosphere.
When fuel evaporates in the fuel tank, fuel bowl (carburetor models) or throttle body (EFI and turbo models), the vapors pass through vent hoses to a charcoal canister. The EFI system, having only 2 hoses to the throttle body, uses an in-line purge solenoid (opens when engine is running) to extract vapors from the canister.
The vapors are stored in the charcoal canister until they are drawn into the intake manifold after the engine begins to run. See Figure and Figure .
Use the Manual With the Right Hardware
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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.
- • You are not confident in the next step or safety outcome.