Abstract: A method, comprising: indicating leakage on a canister side of a fuel system based on a first fuel system pressure following applying a vacuum to the fuel system with a fuel tank isolation valve closed; and indicating leakage on a fuel tank side of the fuel system based on the first fuel system pressure and a second fuel system pressure following applying a vacuum to the fuel system with the fuel tank isolation valve open. In this way, an ELCM with a single reference orifice may be used to perform a leak test with two different thresholds for leak detection. This may allow vehicles currently in production to meet future emissions standards without costly upgrades to the ELCM.

Abstract: A method, comprising: indicating a leak of a first diameter on a canister side of a fuel system following applying a vacuum to the fuel system with a fuel tank isolation valve closed; and indicating a leak of a second diameter on a fuel tank side of the fuel system, based on a vacuum decay in an isolated fuel tank following applying a vacuum to the fuel system with the fuel tank isolation valve open. In this way, an evaporative leak check module with a single reference orifice may be used to determine leaks of multiple sizes in multiple sectors of a fuel system. This may allow current production models to meet more stringent emissions regulations in the future.

Abstract: A method for a fuel system, comprising: during a first condition, purging fuel vapor from a fuel vapor canister to a fuel vapor accumulator; and then during a second condition, evacuating fuel vapor from the fuel vapor accumulator to a fuel tank. The fuel vapor accumulator increases the volume of the fuel system, providing a temporary storage for desorbed fuel vapor. In this way, canister breakthrough of hydrocarbons can be mitigated, thereby reducing bleed emissions.

Abstract: Methods and systems are provided for a latchable refueling valve designed to reduce noise associated with opening and closing the valve. In one example, a system may include a valve armature with first and second latch indices formed on an outer diameter of the armature. The latch indices may be rounded and configured to engage with a latch guide to enable rotation between the armature and the latch guide.

Abstract: Methods and systems are provided for regulating the flow of fuel vapors exiting a fuel tank. In one example, a method for an engine may include adjusting an amount of fuel vapors flowing through a fuel vapor recirculation line, where the recirculation line may be coupled on a first end to a fuel tank and on an opposite second end to a fuel fill inlet. The valve may be adjusted to a more open position to increase fuel vapor flow through the recirculation line in response to increases in hydrocarbon emissions from a fuel vapor canister, and to a more closed position to reduce fuel vapor flow through the recirculation line in response to increases in hydrocarbon emissions from the fuel fill inlet.

Abstract: Methods and systems are provided for purging a fuel vapor canister into an engine intake. A method comprises flowing fuel vapors from a fuel tank through a full length of the fuel vapor canister from a first input to a first output on a first opposite side from the first input. The adsorbed fuel vapors may be purged from the fuel vapor canister through a full width in the fuel vapor canister from a second input to a second output on a second opposite side from the second input.

Abstract: Methods and systems are provided for detecting and mitigating the presence of liquid fuel carryover in an evap system of a vehicle in response to a refueling event. In one example, during a first condition, a vacuum pump is activated to pressurize the fuel system responsive to a first fuel tank pressure decay rate being less than a threshold, and responsive to a second fuel tank pressure decay rate being greater than a threshold, the vacuum pump is maintained on until a fuel tank pressure decreases to atmospheric pressure. In this way, liquid fuel carryover can be quickly and accurately diagnosed, such that mitigating actions may be taken to ensure liquid fuel is returned to the tank prior to contacting the adsorbent material within the vapor canister.

Abstract: Methods and systems are provided for selectively cooling a fuel vapor canister based on vehicle operating conditions, or in response to an anticipated or requested refueling event. In one example, canister cooling elements are powered by solar cells coupled to the vehicle, thereby cooling the canister during conditions wherein bleed emissions are likely to occur. In this way, canister cooling may reduce hydrocarbon vapor bleed emissions without draining the vehicle battery, and may further provide opportunities to advantageously conduct leak tests on the evaporative emissions 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: Systems and methods for operating an engine with a fuel vapor recovery system are disclosed. In one example approach, a method for an engine with a fuel vapor recovery system comprises increasing an amount of flow restriction between storage material in a fuel vapor canister while maintaining a vent valve open during a fuel vapor purging event.

Abstract: Methods and systems are provided for selectively cooling a fuel vapor canister based on vehicle operating conditions, or in response to an anticipated or requested refueling event. In one example, canister cooling elements are powered by solar cells coupled to the vehicle, thereby cooling the canister during conditions wherein bleed emissions are likely to occur. In this way, canister cooling may reduce hydrocarbon vapor bleed emissions without draining the vehicle battery, and may further provide opportunities to advantageously conduct leak tests on the evaporative emissions system.

Abstract: Methods and systems are provided for detecting leaks in an engine fuel system coupled in a vehicle including a first fuel tank and a second fuel tank, and a canister coupled together via a three-way valve. A leak test may be initially performed on the first fuel tank by supplying vacuum to the first fuel tank. The second fuel tank may be tested for leaks immediately following the leak test on the first fuel tank by recycling vacuum from the first fuel tank.

Abstract: Methods and systems are provided for a fuel vapor canister with a modular configuration that may include a number of physically and releasably coupled canister modules, each module including a temperature sensor embedded therein and filled with one of a number of adsorbents. The temperature sensors may be utilized in combination with information regarding module position and the adsorbents within each module to indicate whether one or more of the individual canister modules are not functioning as desired, where such indications are determined during either refueling events, or during canister purging events. In this way, costs associated with servicing fuel vapor canisters may be reduced, the lifetime of fuel vapor canisters may be improved, an overall reduction in undesired evaporative emissions may be achieved, and the capacity of the canister may be readily adjusted based on emissions standards.

Abstract: A method and system for testing an evaporative emission control system for leaks. The method begins by setting a variable reference orifice to a preselected diameter. Then, a vacuum pump evacuates a reference volume in the vicinity of the variable reference orifice. The reference volume is defined by the vacuum pump, and the reference orifice. Then, after a specified evacuation time, the method determines a pressure in the reference volume. That pressure is stored as the threshold test value. The method continues by evacuating the entire EVAP system for a predetermined time. A leak can then be identified if after the evacuation, the system pressure falls at least to the threshold test value. Switching the vacuum pump between the first and second positions is accomplished with a changeover valve having parallel airways configured for evacuating a small volume to the reference orifice and also evacuating the entire EVAP system.

Abstract: Systems and methods to control fuel tank pressure to reduce fuel oxidation in plug-in hybrid electric vehicles are disclosed. A method comprises routing vapors from a fuel system canister to the fuel tank to maintain the fuel tank pressure at a desired pressure. In this way, the engine may be maintained off for greater durations while still retaining fuel quality of fuel stored on-board the vehicle.

Abstract: A method for a fuel system is provided. A vacuum is applied to a fuel vapor canister side of the fuel system, and hydrocarbon breakthrough is indicated responsive to a fuel vapor canister side pressure inflection point indicative of a decay in fuel vapor canister side vacuum. In this way, an evaporative leak check module may perform a leak check on a fuel vapor canister, while hydrocarbon breakthrough from the fuel vapor canister may be indicated without requiring a dedicated hydrocarbon sensor in the canister vent line.

Abstract: A system for an engine, comprising: a fuel tank; a thermal regulator comprising a phase-change material, the thermal regulator coupled to the fuel tank; and an engine coolant passage positioned to transfer thermal energy between engine coolant and the phase-change material. In this way, the temperature of the fuel tank may be managed passively by the phase-change material, and actively by engine coolant, thereby allowing heat energy to be shunted away from the fuel tank, cooling the fuel within the fuel tank, and reducing fuel vapor concentration, thus enabling a fuel vapor canister with a reduced size.

Abstract: Methods and systems are provided for depressurizing a fuel tank prior to refueling the fuel tank. One example method includes adjusting a latchable refueling valve to a latched open position to enable vapor flow from the fuel tank to a vapor canister at a first rate, and responsive to fuel tank pressure being higher than a first pressure threshold after a pre-determined duration at the latched open position, modifying the latchable refueling valve to an unlatched open position. The unlatched open position of the latchable refueling valve enables a second flow rate for fuel vapors, the second flow rate higher than the first flow rate at the latched open position.

Abstract: Systems are provided for a fuel system comprising an external refueling request switch accessible at or near a refueling door, thus enabling methods that may include initiating depressurization of a fuel tank responsive to an operator engaging the refueling request switch. The status of depressurization may be communicated to the operator via on one or more LED displays located either inside the refueling assembly or located at the refueling door. In this way, refueling requests may be initiated by a refueling operator, and by relaying the status of depressurization to the operator, any confusion on the part of the operator may be avoided.

Abstract: Systems and methods for improving fuel vapor purging for a vehicle are presented. In one example, a fuel vapor storage canister vent valve is housed in a fuel vapor storage canister for the purposes of heating contents of the fuel vapor storage canister and venting the fuel vapor storage canister to atmosphere.