Exam 83: Evaporative Emission Control Systems

Two technicians are discussing a state emission test. Technician A says that a vent valve that is not able to close can cause the system to fail the on-board test. Technician B says that a leaking gas cap can cause a failure of the EVAP test. Which technician is correct?

A vehicle fails an emission test due to excessive carbon monoxide indicating a rich air fuel mixture.Technician A says that a saturated charcoal canister could be the cause. Technician B says that a stuck-closed EVAP purge solenoid could be the cause. Which technician is correct?

What polluting chemical compound is caused by evaporating gasoline?

Beginning with the 2000 model year, enhanced EVAP systems were introduced that can detect a leak as small as ________.

Technician A says that low pressure smoke installed in the fuel system can be used to check for leaks. Technician B says that nitrogen under low pressure can be installed in the fuel system to check for leaks. Which technician is correct?

All of the following can increase the pressure in the evaporative emission system EXCEPT ________.

Enhanced EVAP systems that are able to detect fuel vapor leaks were mandated on all U.S. cars starting in ________.

Technician A says that fuel filler caps with pressure and vacuum vents are used with EVAP system fuel tanks. Technician B says that using a non-vented cap on a system equipped with an evaporative emissions system may cause damage to the fuel tank. Which technician is correct?

What is the substance used in a vapor canister to absorb volatile organic compounds?

The canister vent valve is normally ________.

What makes activated charcoal ideal for trapping gasoline fumes?

Which EVAP valve is subject to rust and corrosion more than all of the others?

Technician A says that canister purging occurs during wide open throttle conditions. Technician B says that canister purging uses intake manifold vacuum to pull fuel vapors from the canister. Which technician is correct?

Inadequate purge flow rate will trigger which DTC?

Evaporative emission control systems operate on low pressure measured in inches of water. One psi is equal to how many inches of water?

A fuel tank expansion chamber is designed to be what percentage of the tank capacity?

Which of these components is the EVAP system purge valve?

A small leak is detected by the evaporative emission control system monitor that could be caused by a loose gas cap. Which DTC will likely be set?