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.
On-Board Refueling Vapor Recovery (ORVR)
The ORVR system recovers and stores hydrocarbon fuel vapor that was previously released during refueling. Non ORVR vehicles vent fuel vapors from the tank venting line back to the filler neck and in many states reclaimed by a vacuum receiver (Stage II) on the filling station's fuel pump nozzle.
When refueling, the pressure of the fuel entering the tank forces the hydrocarbon vapors through the tank vent line to the liquid/vapor separator, through the rollover valve and into the charcoal canister.
The HC is stored in the charcoal canister, and the system can then "breathe" through the LDP and the air filter.
ORVR phase in started in the 1998 model year. By model year 2000, all new vehicles sold must be equipped with an ORVR system. The EPA estimates an average of 78 million gallons of gasoline will have been saved from evaporation between the years 1998 and 2020. Additionally, 400,000 tons of smog producing volatile organic compounds (VOC) will be captured annually because of ORVR.
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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.