Where is evaporative emission control system vent circuit on buick regal 1997?

There isn't a single, easily identifiable "evaporative emission control system vent circuit" location on a 1997 Buick Regal. The system is comprised of several components and hoses that work together. The vent line itself is a small hose that connects various parts of the system. It's not usually labeled as such.

To find the vent circuit, you'll need to trace the hoses from the charcoal canister. The charcoal canister is the primary component of the EVAP system and is usually located near the fuel tank, often under the vehicle. From the canister, you'll find hoses leading to:

* The Purge Valve: This valve controls the flow of fuel vapors from the canister to the intake manifold for combustion.

* The Fuel Tank: The vent line allows for pressure equalization in the fuel tank.

* Possibly a Vapor Line Filter: Some systems include a filter along the vapor line.

You'll need a repair manual specific to your 1997 Buick Regal to get the exact routing of the hoses and the location of all components. A Chilton's or Haynes manual would be helpful. These manuals contain diagrams showing the EVAP system and its components.

Without a diagram, visually tracing the lines from the charcoal canister is the best approach, keeping in mind the potential connections listed above. Be aware that working under the car requires proper safety precautions, such as using jack stands and working in a well-ventilated area.