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.
Exhaust Emissions System - EVAP: Operation
When engine is stopped, fuel vapors from fuel tank flow through vapor line into charcoal canister where they are stored. When the engine is running, fresh air drawn through the charcoal canister, creates a vacuum that pulls the stored fuel vapors into the engine.
The roll-over valve, located in the trunk or in the rear left corner pillar, shuts off the fuel ventilation hose, preventing escape of fuel in the event of an accident.
The pressure valve, located in the ventilation hose between filler pipe and charcoal canister, serves to equalize fuel tank pressure and avoid fuel tank collapse.
The fuel tank filler cap contacts a spring loaded valve in the filler neck. Installing the filler cap, opens the valve, allowing fuel vapors to be vented to the charcoal canister when high temperatures cause the fuel to expand.
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
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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.
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