Abstract: A method and system for conducting leak detection in an evaporative emission control system. The method performs a pressure-based leak test at selected intervals. The pressure-based test includes pressurizing the system, using a pump. Then, the system monitors pressure for a selected period. If system pressure falls below a threshold value during the selected period, the system identifies an initial leak. Upon identifying the initial leak, the system substitutes a vacuum-based leak test at each selected interval. The vacuum-based test includes evacuating the system, using the pump. The system then monitors system pressure for a selected period. If system pressure rises above a threshold value during the selected period, then the system identifies a subsequent leak. Upon receiving notification that the initial leak has been repaired, the system returns to pressure-based leak testing. Where a single pump is used, that pump is configured both for system pressurization and evacuation.

Abstract: An evaporative emission control system for a plug-in hybrid electric vehicle that indicates the level of loading of a carbon canister of the system. The system has multiple thermocouples positioned space apart from each other along a vapor flow path within the carbon canister. A controller is connected to each thermocouple, which monitors the temperature of the thermocouples. The controller indicates the level of saturation of the carbon canister based on certain pre-determined temperature criteria.

Abstract: Methods and systems are provided for identifying leaks on each of a fuel tank and a canister side of a fuel system using a single leak check module. A position of a switching valve coupled in the vapor line of the fuel system is adjusted to selectively couple the leak check module to either the fuel tank or the canister. Leak is detected based on a change in pressure at a reference orifice of the leak check module following applying of vacuum from a vacuum pump.

Abstract: A method for diagnosing a fault within a evaporative emission control system of an automotive vehicle. The method monitors the carbon canister temperature during a system leak test. The leak test here is undertaken with the engine running, and engine vacuum is employed to evacuate the EVAP system. If the evacuation succeeds in reaching a target vacuum, and a temperature gain in the canister is observed, then the system infers proper system operation. Failure to achieve a target vacuum causes the system to determine a likely cause of the failure based on the temperature response of the carbon canister.

Abstract: A method for detecting blockage within a recirculation tube of the evaporative emission control system of a PHEV measures the rise in interior temperature of a canister of the EVAP system, during the process of refueling, and notes an initial state of loading of the canister before refueling, indicative of the amount of hydrocarbons contained within the canister It is inferred that the recirculation tube is operative reliably if the rise in canister temperature is below a pre-determined temperature value.

Abstract: A system for a vehicle, comprising: a tank pressure control valve coupled in a first conduit between a fuel tank and a fuel vapor canister; a refueling valve coupled in a second, different, conduit between the fuel tank and the fuel vapor canister, the second conduit in parallel to the first conduit. In this way, two smaller, less complex valves may be utilized to control fuel tank vapor purging and fuel tank depressurization during refueling. This in turn may lower system cost and increase system functionality.

Abstract: Methods and systems for fuel system leak detection are disclosed. In one example approach, a method comprises, in response to a pressure change in a fuel tank less than a threshold for a duration during engine-off conditions while the tank is sealed off from atmosphere, indicating a leak condition, and in response to a pressure change in the tank greater than the threshold during engine-off conditions while the tank is sealed off from atmosphere, indicating a no-leak condition.

Abstract: A capless nozzle for a vehicle fuel filler canal, includes a conical portion; and a non-conical portion having a stop formed therein configured to limit travel of a filler pipe in one direction when the pipe is inserted in the filler canal.

Abstract: System for detecting leakage within a canister purge valve of an evaporative emission control system. The system includes a power train control module connected to the canister purge valve, configured to command the canister purge valve between open and closed positions. In addition, the system includes a flow meter having an inlet and an outlet. The inlet is in fluid communication with ambient air surrounding the vehicle, and the outlet is in fluid communication with an inlet of the canister purge valve. The system further includes a control module operatively connected to the flow meter. The control module is programmed to analyze flow through the flow meter; compare the measured flow to predetermined flow data; and to indicate whether that flow exceeds a predetermined level.

Abstract: Methods and systems for fuel system leak detection are disclosed. In one example approach, a method comprises, during an engine-on condition, delivering fuel from a fuel tank to one or more cylinders of the engine while the fuel tank is sealed off from atmosphere, and indicating a leak based on pressure in the fuel tank. For example, a leak may be indicated in response to a pressure decrease in the fuel tank greater than an expected pressure decrease, where the expected pressure decrease is based on a fuel level in the fuel tank.

Abstract: Methods and systems for detecting a leak in a canister purge valve are disclosed. In one example approach, a method comprises indicating a leak in response to a temperature change in a fuel vapor canister coupled to a fuel tank in an emission control system while the engine is in operation and a purge valve is closed.

Abstract: Methods and systems for detecting a refueling event for diagnostics are disclosed. In one example approach a method comprises discontinuing leak diagnostics in response to a temperature change in a fuel vapor canister coupled to a fuel tank in an emission control system while the leak diagnostics are being performed in the emission control system.

Abstract: Methods and systems are provided for accurately confirming fuel tank depressurization before unlocking a fuel door to enable refueling. Following a refueling request, a fuel system may be sealed from the atmosphere while one or more fuel system valves are adjusted to divert fuel tank pressure or vacuum to an engine intake. Depressurization may be inferred based on the presence of air or vapor flow into the intake as sensed by a manifold airflow sensor.

Abstract: Methods and systems for inferring a fuel level in a fuel tank based on temperature changes in a carbon canister are disclosed. In one example approach a method comprises, indicating a fuel level in a fuel tank based on a temperature change of adsorbent in a carbon canister during refueling.

Abstract: Methods and systems for controlling a locking mechanism on a fuel cap for refueling a vehicle are disclosed. In one example approach, a method comprises venting a fuel tank into a vapor absorbent canister in response to a request to refuel and unlocking the fuel cap in response to a predetermined temperature change in said canister.

Abstract: A method for desorbing fuel vapors from a canister of a vehicle having an internal combustion engine and a fuel tank includes detecting the temperature within the interior of the fuel tank using a temperature sensor positioned within the fuel tank. The canister is in fluid communication with the fuel tank and an intake manifold of the engine of the vehicle. A vapor bypass valve is positioned along a flow line between the fuel tank and the canister. The vapor bypass valve is opened if the temperature inside the fuel tank falls below a pre-determined value. The low pressure region created within the fuel tank due to fall in temperature is utilized to route ambient air along with the fuel-vapors contained within the canister, towards the fuel tank, through the opened vapor bypass valve.

Abstract: Systems and methods for internal orifice characterization in an evaporative leak check module are disclosed. In one example approach, a method comprises operating a pump to draw air from an emission control system through an orifice to obtain a reference pressure, and indicating a leak in response to pressure in the emission control system remaining above a threshold pressure while operating the pump to decrease pressure in the emission control system, where the threshold pressure is based on a coded indication and the reference pressure.

Abstract: Methods and systems for detecting a refueling event for diagnostics are disclosed. In one example approach a method comprises discontinuing leak diagnostics in response to a temperature change in a fuel vapor canister coupled to a fuel tank in an emission control system while the leak diagnostics are being performed in the emission control system.

Abstract: Methods and systems for purging a hydrocarbon trap in an engine intake in a vehicle are disclosed. In one example approach, a method comprises during an engine off condition, operating a pump in a purge line coupled to a fuel vapor canister in an emission control system to deliver fuel stored in a hydrocarbon trap in an intake of the engine to the fuel vapor canister.

Abstract: Methods and systems for passively purging a hydrocarbon trap in an engine intake in a vehicle are disclosed. In one example approach, a method comprises, in response to an ambient temperature decrease during an engine off condition while a fuel tank is sealed from atmosphere, delivering fuel stored in a hydrocarbon trap in an intake of the engine to a fuel vapor canister coupled to the fuel tank in an emission control system.