System and method for fuel refilling relief valve

Abstract

The present disclosure provides systems and methods for fuel refill relief valves. Methods and systems are provided for diagnosing a fuel refill relief valve positioned along a passage extending from an exhaust system to a fuel tank. The method may include commanding the fuel refill relief valve to open while monitoring flow through a particulate filter via a differential pressure sensor.

Description

Technical Field

[0001] The present description generally relates to methods and systems for diagnosing a fuel refill pressure relief valve (FRPRV) of an evaporative emission control (EVAP) system. Background Art

[0002] A hybrid vehicle may include a fuel tank configured to store fuel vapor during daytime heating and cooling, so that daytime fuel vapor may not have to be stored in a carbon-filled fuel vapor storage canister. However, storing fuel vapor in the fuel tank instead of in a carbon-filled canister may cause the pressure in the fuel tank to rise when the fuel is heated and fall when the fuel is cooled. One way to prevent fuel vapor from escaping through the fuel inlet port when the fuel inlet port is opened before refueling may be to open a valve and allow fuel vapor to leave the fuel tank or allow air to enter the fuel tank so that when the fuel inlet port is opened, the pressure inside the fuel tank is substantially atmospheric pressure. It may be undesirable to discharge fuel vapor directly to the atmosphere because hydrocarbons may be regulated emissions. In addition, a large volume of a carbon-filled fuel vapor storage canister may be required to capture all hydrocarbons that may leave the fuel tank during fuel refilling. Therefore, it may be desirable to treat the fuel vapor so that they are not allowed to enter the atmosphere. One way to treat the fuel vapor may be to release the fuel vapor from the fuel tank to a catalyst in the exhaust system of the engine so that the catalyst can treat the fuel vapor. However, directing fuel vapors to a catalyst for treatment may add valves and vapor lines to the vehicle's evaporative emissions system. Regulatory entities may specify that the valves and their associated vapor lines be continuously evaluated to allow operation of the vehicle. Summary of the invention

[0003] In one example, a component of an exhaust system may be diagnosed via a method for an engine that includes activating a pump and commanding opening of a fuel refill pressure relief valve in response to a request to diagnose a fuel refill pressure relief valve positioned along a first passage between an engine exhaust system and a fuel tank.

[0004] By activating the pump and commanding the fuel refill pressure relief valve to open, a technical result of determining whether the fuel refill pressure relief valve may be operating as expected can be provided. Specifically, flow through the exhaust system and into the evaporative emissions system can indicate a properly opened fuel refill pressure relief valve. Similarly, cessation of flow from the exhaust system to the evaporative emissions system can indicate a properly closed fuel refill pressure relief valve.

[0005] The present method provides several advantages. First, the method allows diagnosis of the operation of a fuel refill pressure relief valve in order to meet enacted vehicle emission regulations. In addition, the method can provide for specific identification of the operation of one or more emission devices. Furthermore, the method can be performed without additional hardware, thereby controlling the financial cost of the method.

[0006] It will be appreciated that the above summary is provided to introduce in simplified form a series of concepts further described in the detailed description. This is not meant to identify key or essential features of the claimed subject matter, the scope of which is uniquely defined by the claims following the detailed description. Furthermore, the claimed subject matter is not limited to embodiments that address any disadvantages mentioned above or in any part of this disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 A high-level block diagram illustrating an exemplary vehicle system is shown.

[0008] Figure 2 Shown included in Figure 1 Schematic diagram of a fuel system and evaporative emissions control (EVAP) system in an exemplary vehicle system.

[0009] Figure 3 and Figure 4 A flow chart is shown of an exemplary method for operating a vehicle and its evaporative emissions system.

[0010] Figure 5 Shown with Figure 3 and Figure 4 Methods of collaboration Figure 1 and Figure 2 An exemplary operating sequence of the system. DETAILED DESCRIPTION

[0011] The following description relates to systems and methods for diagnosing the integrity of a fuel refill pressure relief valve (FRPRV) of an evaporative emission control (EVAP) system of an engine. The engine may be included as part of a vehicle system, such as Figure 1 The engine can be connected to the EVAP system and the fuel system, such as Figure 2 shown. Figure 1 and Figure 2 The system can be based on Figure 3 and Figure 4 Method operation. Figure 1 and Figure 2 systems and Figure 3 and Figure 4 The method can be as follows Figure 5 The operations are performed as shown in the operation sequence.

[0012] Figure 1 An exemplary vehicle propulsion system 100 is shown. The vehicle propulsion system 100 includes an internal combustion engine 110 and a motor 120 (e.g., an electric machine). The motor 120 may be configured to utilize or consume a different energy source than the engine 110. For example, the engine 110 may consume a liquid fuel (e.g., gasoline) to produce an engine output, while the motor 120 may consume electrical energy to produce a motor output. Therefore, a vehicle having the propulsion system 100 may be referred to as a hybrid electric vehicle (HEV).

[0013] The vehicle propulsion system 100 may utilize a variety of different operating modes depending on the operating conditions encountered by the vehicle propulsion system. Some of these modes may enable the engine 110 to be maintained in an off state, in other words, set to a deactivated state, wherein fuel combustion via the engine is stopped. For example, under selected operating conditions, the motor 120 may propel the vehicle via the drive wheels 130 as indicated by arrow 122, while the engine 110 is deactivated.

[0014] During other operating conditions, the engine 110 may be set to a deactivated state (as described above), while the motor 120 may be operated to charge the energy storage device 150. For example, as indicated by arrow 122, the motor 120 may receive wheel torque from the drive wheel 130, wherein the motor may convert the kinetic energy of the vehicle into electrical energy to be stored at the energy storage device 150 as indicated by arrow 124. This operation may be referred to as regenerative braking of the vehicle. Thus, in some embodiments, the motor 120 may provide a generator function. However, in other embodiments, the generator 160 may alternatively receive wheel torque from the drive wheel 130, wherein the generator may convert the kinetic energy of the vehicle into electrical energy to be stored at the energy storage device 150 as indicated by arrow 162.

[0015] During still other operating conditions, the engine 110 may be operated by combusting fuel received from the fuel system 140 as indicated by arrow 142. For example, when the motor 120 is deactivated, the engine 110 may be operated to propel the vehicle via the drive wheels 130 as indicated by arrow 112. During other operating conditions, both the engine 110 and the motor 120 may each be operated to propel the vehicle via the drive wheels 130 as indicated by arrows 112 and 122, respectively. A configuration in which both the engine and the motor may selectively propel the vehicle may be referred to as a parallel vehicle propulsion system. It should be noted that in some embodiments, the motor 120 may propel the vehicle via a first set of drive wheels, while the engine 110 may propel the vehicle via a second set of drive wheels.

[0016] In other embodiments, the vehicle propulsion system 100 may be configured as a series-type vehicle propulsion system, in which the engine does not directly propel the drive wheels. Instead, the engine 110 may be operated to power the motor 120, which in turn may propel the vehicle via the drive wheels 130, as indicated by arrow 122. For example, during selected operating conditions, the engine 110 may drive the generator 160 as indicated by arrow 116, which in turn may supply electrical energy to one or more of the following: the motor 120 as indicated by arrow 114 or the energy storage device 150 as indicated by arrow 162. As another example, the engine 110 may be operated to drive the motor 120, which in turn may provide a generator function to convert the engine output into electrical energy, where the electrical energy may be stored at the energy storage device 150 for subsequent use by the motor.

[0017] The fuel system 140 may include one or more fuel storage tanks 144 for storing fuel on the vehicle, such as a sealed non-pressure non-integrated fuel supply canister dedicated system (NIRCOS) fuel tank. For example, the fuel tank 144 can store one or more liquid fuels, including but not limited to: gasoline, diesel and alcohol fuels. In some examples, the fuel can be stored on the vehicle as a blend of two or more different fuels. For example, the fuel tank 144 can be configured to store a blend of gasoline and ethanol (e.g., E10, E85, etc.) or a blend of gasoline and methanol (e.g., M10, M85, etc.), whereby these fuels or fuel blends can be delivered to the engine 110, as indicated by arrow 142. Some other suitable fuels or fuel blends can be supplied to the engine 110, where they can be burned at the engine to produce an engine output. The engine output can be used to propel the vehicle as indicated by arrow 112 or to recharge the energy storage device 150 via a motor 120 or a generator 160.

[0018] In some embodiments, energy storage device 150 may be configured to store electrical energy that may be supplied to other electrical loads resident on the vehicle (in addition to the motor), including cabin heating and air conditioning, engine starting, headlights, cabin audio and video systems, etc. As a non-limiting example, energy storage device 150 may include one or more batteries and / or capacitors.

[0019] The control system 190 may communicate with one or more of the engine 110, the motor 120, the fuel system 140, the energy storage device 150, and the generator 160. The control system 190 may receive sensory feedback information from one or more of the engine 110, the motor 120, the fuel system 140, the energy storage device 150, and the generator 160. In addition, the control system 190 may send control signals to one or more of the engine 110, the motor 120, the fuel system 140, the energy storage device 150, and the generator 160 in response to this sensory feedback. The control system 190 may receive an indication of an operator-requested output of the vehicle propulsion system from the vehicle operator 102. For example, the control system 190 may receive sensory feedback from a pedal position sensor 194 that communicates with a pedal 192. The pedal 192 may schematically refer to a brake pedal, or alternatively, a driver demand pedal.

[0020] As indicated by arrow 184, energy storage device 150 may periodically receive electrical energy from a power source 180 that resides outside the vehicle (e.g., not part of the vehicle). As a non-limiting example, vehicle propulsion system 100 may be configured as a plug-in hybrid electric vehicle (HEV), such that electrical energy may be supplied to energy storage device 150 from power source 180 via power transmission cable 182. During operation to recharge energy storage device 150 from power source 180, power transmission cable 182 may electrically couple energy storage device 150 and power source 180. When the vehicle propulsion system is operating to propel the vehicle, power transmission cable 182 may be disconnected between power source 180 and energy storage device 150. Control system 190 may identify and / or control the amount of electrical energy stored at the energy storage device, which amount of electrical energy may be referred to as a state of charge (SOC).

[0021] In other embodiments, the power transmission cable 182 may be omitted, where the power may be received wirelessly at the energy storage device 150 from the power source 180. For example, the energy storage device 150 may receive power from the power source 180 via one or more of electromagnetic induction, radio waves, and electromagnetic resonance. Thus, it will be appreciated that any suitable method may be used to recharge the energy storage device 150 from a power source that is not part of the vehicle, such as from solar or wind power. In this way, the motor 120 may propel the vehicle by utilizing an energy source different from the fuel utilized by the engine 110.

[0022] The fuel system 140 may periodically receive fuel from a fuel source residing outside the vehicle. As a non-limiting example, the vehicle propulsion system 100 may be refueled by receiving fuel via the fuel dispensing device 170, as indicated by arrow 172. In some embodiments, the fuel tank 144 may be configured to store the fuel received from the fuel dispensing device 170 until it is supplied to the engine 110 for combustion. In some embodiments, the control system 190 may receive an indication of the level of fuel stored at the fuel tank 144 via a fuel level sensor. The fuel level stored at the fuel tank 144 (e.g., as identified by the fuel level sensor) may be communicated to the vehicle operator, for example, via a fuel gauge or an indication in the vehicle instrument panel 196.

[0023] The vehicle propulsion system 100 may also include an ambient temperature / humidity sensor 198 and a roll stability control sensor, such as a lateral and / or longitudinal and / or yaw rate sensor 199. The vehicle dashboard 196 may include indicator lights and / or a text-based display in which messages are displayed to the operator. The vehicle dashboard 196 (human / machine interface) may also include various input portions for receiving operator input, such as buttons, a touch screen, voice input / recognition, etc. For example, the vehicle dashboard 196 may include a refueling button 197 that the vehicle operator may manually actuate or press to initiate refueling. For example, as described in more detail below, in response to the vehicle operator actuating the refueling button 197, the fuel tank 144 in the vehicle may be depressurized so that refueling can be performed.

[0024] Reference now Figure 2 , a schematic diagram 200 depicting a vehicle system 206 is shown. In some examples, the vehicle system 206 may be a HEV system, such as a PHEV system. For example, the vehicle system 206 may be connected to Figure 1 However, in other examples, vehicle system 206 may be implemented in a non-hybrid vehicle (eg, equipped with an engine but without a motor operable to at least partially propel the vehicle).

[0025] The vehicle system 206 may include an engine system 208 coupled to each of an evaporative emission control (EVAP) system 251 and a fuel system 140. The engine system 208 may include an engine 110 having a plurality of cylinders 230. The engine 110 may include an engine intake system 223 and an engine exhaust system 225. Each cylinder may include an intake poppet valve 260 and an intake poppet valve actuator 261. The intake poppet valve actuator 261 may be electrically, mechanically, or hydraulically operated, and if desired, it may maintain the intake valve in an open or closed position throughout the cycle of the engine. Similarly, each cylinder may include an exhaust poppet valve 264 and an exhaust poppet valve actuator 265. The exhaust poppet valve actuator 265 may be electrically, mechanically, or hydraulically operated, and if desired, it may maintain the exhaust valve in an open or closed position throughout the cycle of the engine. The engine intake system 223 may include a throttle valve 262 in fluid communication with an engine intake manifold 244 via an intake passage 242. In addition, the engine intake system 223 may include an air box and a filter (not shown) positioned upstream of the throttle 262. The engine exhaust system 225 may include an exhaust manifold 248 leading to an exhaust passage 235 that directs exhaust gas to the atmosphere. The engine exhaust system 225 may include an electrically heated catalyst 226 and an emission control device 270, which may include one or more exhaust catalysts. For example, the emission control device 270 may include a three-way catalyst, a lean nitrogen oxide (NOx) x ) one or more of a trap, a particulate filter, an oxidation catalyst, etc. In some examples, flow through emission control device 270 may be sensed via differential pressure sensor 282 .

[0026] It should be understood that other components such as various valves and sensors may be included in the engine system 208. For example, a barometric pressure sensor 213 may be included in the engine intake system 223. In one example, the barometric pressure sensor 213 may be a manifold air pressure (MAP) sensor and may be coupled to the engine intake manifold 244 downstream of the throttle 262. The barometric pressure sensor 213 may rely on a part throttle or a wide open or wide open throttle condition, for example, when the opening of the throttle 262 is greater than a threshold value, in order to accurately determine the barometric pressure. In addition, the engine system may also include an ambient temperature sensor (not shown).

[0027] Fuel system 140 may include a fuel tank 144 coupled to a fuel pump system 221. Fuel pump system 221 may include one or more pumps for supplying fuel to cylinder 230 via fuel injector 266 (although in Figure 2Only a single fuel injector 266 is shown, but additional fuel injectors may be provided for each cylinder 230) to pressurize the fuel delivered to the cylinder 230. The distribution or relative amounts of the delivered fuel, injection timing, etc. may vary with operating conditions such as engine load, engine knock, exhaust temperature, etc. in response to different operating or degradation states of the fuel system 140, the engine 110, etc. The pressure in the fuel system may be estimated via a fuel tank pressure transducer (FTPT) 156. In one example, the FTPT 156 may be included in the fuel tank 144.

[0028] Fuel system 140 can be any of a returnless fuel system, a return fuel system, or various other types of fuel systems. Fuel tank 144 can store fuel 224, which includes a variety of fuel blends (e.g., fuels with a range of alcohol concentrations), such as gasoline, various gasoline-ethanol blends (including E10, E85), etc. A fuel level sensor 234 disposed in fuel tank 144 can provide an indication of fuel level ("fuel level input") to a controller 212 included in control system 190. As depicted, fuel level sensor 234 can include a float coupled to a variable resistor. Alternatively, other types of fuel level sensors can be used.

[0029] Vapors generated in the fuel system 140 may be directed to the EVAP system 251 via a first conduit 271 extending between the fuel tank 144 and the carbon-filled fuel vapor storage canister 222. Fuel vapors stored in the fuel tank 144 may be directed to the electrically heated catalyst 226 via a second conduit 278. Fuel vapors stored in the carbon-filled fuel vapor storage canister 222 may be directed to the intake manifold 244 via a third conduit 228 (e.g., a passage). A fourth conduit 227 (e.g., a passage) extends between the carbon-filled fuel vapor storage canister 222 and an atmospheric port 239.

[0030] A fuel tank isolation valve (FTIV) 252 for isolating the fuel tank during certain conditions is shown positioned along first conduit 271. For example, during engine operation, FTIV 252 may remain closed to reduce the amount of diurnal vapor or "running loss" vapor directed from fuel tank 144 to charcoal-filled fuel vapor storage canister 222. During refueling operations and selected purging conditions, FTIV 252 may be temporarily opened, such as for a certain duration, to direct fuel vapor from fuel tank 144 to charcoal-filled fuel vapor storage canister 222. Additionally, FTIV 252 may also be temporarily opened when fuel tank pressure is above a threshold (e.g., above the mechanical pressure limit of the fuel tank) so that fuel vapor may be released into charcoal-filled fuel vapor storage canister 222 and maintain the fuel tank pressure below the threshold.

[0031] The EVAP system 251 may also include a fuel refill pressure relief valve (FRPRV) 218 ​​configured in parallel with the FTIV 252. As part of the NIRCOS fuel system, the FRPRV 218 may be a normally closed valve. The FRPRV 218 may be controlled by the controller using a pulse width modulation cycle to control the pressure when refueling the fuel tank 144. The electrically heated catalyst 226 may be activated before opening the FRPRV so that fuel vapors may be processed via the electrically heated catalyst 226.

[0032] like Figure 2 , FRPRV 218 and FTIV 252 are shown as being external to the fuel tank, but it is understood that in other examples, FRPRV 218 and FTIV 252 and sections of first and second conduits 271 and 278 may be fully contained within the fuel tank without departing from the scope of the present disclosure.

[0033] In some examples, refueling system 219 may include a fuel tank cap 205 for sealing the refueling system from the atmosphere. Refueling system 219 may be coupled to fuel tank 144 via fuel filler pipe 211. During refueling, fuel tank cap 205 may be opened manually, or may be opened automatically in response to a refueling request received at controller 212. A fuel dispensing device (e.g., Figure 1 170) may be received by and thereafter fluidly coupled to the refueling system 219, whereby fuel may be supplied to the fuel tank 144 via the fuel filler pipe 211. Refueling may continue until the fuel dispensing device is manually shut off or until the fuel tank 144 is filled to a threshold fuel level (e.g., until feedback from the fuel level sensor 234 indicates that the threshold fuel level has been reached), at which point a mechanical or otherwise automatic stop of the fuel dispensing device may be triggered.

[0034] The EVAP system 251 may include one or more emission control devices, such as a carbon-filled fuel vapor storage canister 222 filled with a suitable adsorbent configured to temporarily capture fuel vapors (including vaporized hydrocarbons) during refueling operations. In one example, the adsorbent used may be activated carbon. The EVAP system 251 may also include a canister vent path or via a fourth conduit 227 that may vent gases from the carbon-filled fuel vapor storage canister 222 to the atmosphere when storing or capturing fuel vapors from the fuel system 140.

[0035] The carbon-filled fuel vapor storage canister 222 may include a buffer zone 222a (or buffer region), each of the carbon-filled fuel vapor storage canister and the buffer zone including an adsorbent. As shown, the volume of the buffer zone 222a may be less than the volume of the carbon-filled fuel vapor storage canister 222 (e.g., be a portion thereof). The adsorbent in the buffer zone 222a may be the same as or different from the adsorbent in the carbon-filled fuel vapor storage canister 222 (e.g., both may include charcoal). The buffer zone 222a may be located within the carbon-filled fuel vapor storage canister 222 such that during canister loading, fuel tank vapors may first be adsorbed within the buffer zone, and then when the buffer zone is saturated, additional fuel tank vapors may be adsorbed in the remaining volume of the carbon-filled fuel vapor storage canister. In contrast, during purging of the carbon-filled fuel vapor storage canister 222, fuel vapor may first be desorbed from the carbon-filled fuel vapor storage canister (e.g., to a threshold amount) before desorbing from the buffer zone 222a. In other words, the loading and unloading of buffer zone 222a may not coincide with the loading and unloading of carbon-filled fuel vapor storage canister 222. Thus, one function of buffer zone 222a is to inhibit any fuel vapor peaks from flowing from fuel tank 144 to carbon-filled fuel vapor storage canister 222, thereby reducing the likelihood of any fuel vapor peaks traveling to engine 110.

[0036] In some examples, one or more temperature sensors 232 may be coupled to and / or within the carbon-filled fuel vapor storage canister 222. When the adsorbent in the carbon-filled fuel vapor storage canister 222 adsorbs fuel vapor, heat (adsorption heat) may be generated. Similarly, when the adsorbent in the carbon-filled fuel vapor storage canister 222 desorbs fuel vapor, heat may be consumed. In this way, the adsorption and desorption of fuel vapor by the carbon-filled fuel vapor storage canister 222 may be monitored and estimated based on temperature changes within the carbon-filled fuel vapor storage canister. In addition, one or more canister heating elements 236 may be coupled to and / or within the carbon-filled fuel vapor storage canister 222. The canister heating element 236 may be used to selectively heat the canister (and the adsorbent contained therein) prior to performing a purge operation, so as to, for example, enhance the desorption of fuel vapor. The canister heating element 236 may include an electrical heating element, such as an electrically conductive metal, ceramic, or carbon element that may be electrically heated, such as a thermistor. In some embodiments, the canister heating element 236 may include a microwave energy source, or may include a canister jacket coupled to a hot air source or hot water source. The canister heating element 236 may be coupled to one or more heat exchangers that may facilitate the transfer of heat (e.g., from hot exhaust) to the carbon-filled fuel vapor storage canister 222. The canister heating element 236 may be configured to heat the air within the carbon-filled fuel vapor storage canister 222 and / or directly heat the adsorbent within the carbon-filled fuel vapor storage canister 222. In some embodiments, the canister heating element 236 may be included in a heater compartment coupled to the interior or exterior of the carbon-filled fuel vapor storage canister 222. In some embodiments, the carbon-filled fuel vapor storage canister 222 may be coupled to one or more cooling circuits and / or cooling fans. In this way, the carbon-filled fuel vapor storage canister 222 may be selectively cooled to enhance adsorption of fuel vapor (e.g., before a refueling event). In some examples, canister heating element 236 may include one or more Peltier elements that may be configured to selectively heat or cool carbon-filled fuel vapor storage canister 222 .

[0037] Fourth conduit 227 may also allow fresh air to be drawn into charcoal filled fuel vapor storage canister 222 while stored fuel vapors are purged from fuel system 140 to engine intake system 223 via third conduit 228 and canister purge valve (CPV) 291. For example, CPV 291 may be a normally closed valve, but may be opened during certain conditions so that vacuum from engine intake manifold 244 may be provided to charcoal filled fuel vapor storage canister 222 for purging. In some examples, fourth conduit 227 may also include air filter 259 disposed therein downstream of charcoal filled fuel vapor storage canister 222.

[0038] In some examples, the EVAP system 251 may also include an evaporative level check monitor (ELCM) 295. The ELCM 295 may be disposed in the fourth conduit 227 between the carbon-filled fuel vapor storage canister 222 and the air filter 259 and may be configured to control ventilation and / or assist in the detection of undesirable evaporative emissions. As an example, the ELCM 295 may include a vacuum pump 296 for applying negative pressure to the fuel system when testing for undesirable evaporative emissions. In some embodiments, the vacuum pump may be configured to be reversible. In other words, the vacuum pump may be configured to apply negative or positive pressure to the EVAP system 251 and the fuel system 140.

[0039] The controller 212 may intermittently perform a routine to detect undesirable evaporative emissions on the fuel system 140 to confirm that the fuel system has not degraded. Thus, the undesirable evaporative emissions detection routine may be performed when the engine is off (engine off degradation test) using the engine off natural vacuum (EONV) generated due to changes in temperature and pressure at the fuel tank after the engine is stopped and / or the vacuum supplemented from the vacuum pump. Alternatively, the undesirable evaporative emissions detection routine may be performed while the engine is running by operating the vacuum pump and / or using the engine intake manifold vacuum. The test for undesirable evaporative emissions may be performed by the ELCM 295 communicatively coupled to the controller 212.

[0040] The fuel system 140 may be a non-integrated refueling canister dedicated system (NIRCOS) because the fuel tank 144 may be substantially isolable from the carbon-filled fuel vapor storage canister 222, such that the fuel vapor in the fuel tank 144 and the carbon-filled fuel vapor storage canister 222 may be independently controlled as desired (e.g., during refueling). During the period when the fuel tank 144 is fluidly separated from the carbon-filled fuel vapor storage canister 222, fuel vapor pressure may build up within the fuel tank. Therefore, venting and decompression control routines are typically implemented for the NIRCOS fuel tank and its structural reinforcements. For example, a given NIRCOS may include a plurality of valves and vent lines coupled to one or more fuel tanks included therein to ensure that any excess fuel vapor pressure is properly vented or redistributed. In addition, the NIRCOS fuel tank may be constructed of a high tensile strength material (such as heavy steel) and configured with a plurality of supports extending between opposing walls of a given NIRCOS fuel tank so that greater fuel vapor pressures may be withstood without fuel tank degradation.

[0041] Fuel system 140 may be operated in a plurality of modes by controller 212 by selectively adjusting various valves (e.g., in response to various sensors). For example, fuel system 140 may be operated in a refueling mode (e.g., when a vehicle operator requests a refueling), wherein controller 212 may close FTIV 252. Additionally, fuel system 140 may be operated in an exhaust mode. In exhaust mode, controller 212 may open FTIV 252 and canister vent valve 229 while maintaining CPV 291 closed to direct refueling vapors into charcoal-filled fuel vapor storage canister 222 while preventing fuel vapors from being directed into engine intake manifold 244 (and thereby providing an exhaust path for fuel vapors). Thus, opening FTIV 252 may allow refueling vapors to be stored in charcoal-filled fuel vapor storage canister 222. After refueling is complete, at least FTIV 252 may be closed again.

[0042] As another example, the fuel system may be operated in a canister purge mode (e.g., after a given emission control device light-off temperature has been reached and the engine 110 is running), wherein the controller 212 may open the CPV 291 and the canister vent valve 229 while closing the FTIV 252. Herein, the vacuum generated by the engine intake manifold 244 of the (operating) engine 110 may be used to draw fresh air through the fourth conduit 227 and through the charcoal-filled fuel vapor storage canister 222 to purge the stored fuel vapor into the engine intake manifold 244. Thus, in the canister purge mode, the fuel vapor purged from the charcoal-filled fuel vapor storage canister 222 may be combusted in the engine 110. The canister purge mode may be continued until the amount or level of fuel vapor stored in the charcoal-filled fuel vapor storage canister 222 is below a threshold amount or level.

[0043] In yet another example, the fuel system may be operated in a pressure relief mode during fuel refill of the fuel tank 144, whereby the fuel vapors may be processed via the electrically heated catalyst 226 when the engine 110 is not combusting air and fuel. Specifically, when a refill of the fuel tank 144 is requested, the FTIV 252 may be closed and the FRPRV 218 may be opened to allow the fuel vapors in the fuel tank 144 to be combusted within the electrically heated catalyst 226. The vacuum pump 296 may be activated to draw the fuel vapors from the fuel tank 144 through the electrically heated catalyst during the fuel tank refill. This may allow the fuel vapors to be processed (e.g., combusted) while the carbon-filled fuel vapor storage canister 222 is filled with fuel vapors, thereby reducing the likelihood of hydrocarbons being released into the atmosphere.

[0044] The control system 190 including the controller 212 is shown as receiving information from a plurality of sensors 216 (various examples of which are described herein) and sending control signals to a plurality of actuators 281 (various examples of which are described herein). The controller 212 may be configured as a powertrain control module (PCM). As an example, the sensors 216 may include one or more of an exhaust gas sensor 237 located upstream of the emission control device 270 in the exhaust passage 235, a temperature sensor 233 located downstream of the emission control device 270 in the exhaust passage 235, a fuel level sensor 234 located in the fuel tank 144, a temperature sensor 232 located in the carbon-filled fuel vapor storage canister 222, and the FTPT 156. Other sensors (such as pressure, temperature, air-fuel ratio, and composition sensors) may be coupled to various locations in the vehicle system 206. As additional or alternative examples, the actuators 281 may include the fuel injector 266, the throttle 262, the FTIV 252, the CPV 291, and the FRPRV 286. Controller 212 may receive input data from sensor 216 , process the input data, and trigger actuator 281 in response to the processed input data based on instructions or code programmed into non-transitory memory therein, the instructions or code corresponding to one or more control routines.

[0045] therefore, Figure 1 and Figure 2A system for a vehicle is provided, the system comprising: an internal combustion engine including an exhaust system; a fuel tank; an evaporative emission system including a pump and a fuel refilling pressure relief valve, the fuel refilling pressure relief valve being positioned along a first passage extending between the fuel tank and the exhaust system; a controller including executable instructions stored in a non-transitory memory, the executable instructions causing the controller to diagnose the fuel refilling pressure relief valve via activating the pump. In a first example, the system further comprises additional executable instructions causing the controller to monitor flow through the fuel refilling pressure relief valve. In a second example, which may include the first example, the system further comprises a differential pressure sensor. In a third example, which may include one or both of the first and second examples, the system comprises: wherein flow through the fuel refilling pressure relief valve is monitored by a differential pressure sensor. In a fourth example, which may include one or more of the first to third examples, the system comprises: wherein the differential pressure sensor is configured to sense pressure on a particulate filter. In a fifth example, which may include one or more of the first to fourth examples, the system further comprises additional executable instructions causing the controller to command opening of the fuel refilling pressure relief valve to diagnose the fuel refilling pressure relief valve. In a sixth example, which may include one or more of the first to fifth examples, the system further includes a fuel tank isolation valve and additional executable instructions for commanding opening of the fuel tank isolation valve to diagnose the fuel refill pressure relief valve. In a seventh example, which may include one or more of the first to sixth examples, the system includes: wherein activating the pump causes gas to be drawn from the exhaust system to the pump.

[0046] Now turn to Figure 3 and Figure 4 , a high-level flowchart of an exemplary method 300 for operating an EVAP system is shown. The method 300 may be implemented at least in part as stored in a computer such as a Figure 1 and Figure 2 The executable instructions in the non-transitory memory of the controller in the system shown. In addition, Figure 2 and Figure 4 Methods may include taking actions in the physical world to transform the system (e.g. Figure 1 and Figure 2 In addition, the method 300 can be combined with Figure 1 and Figure 2 The systems shown perform collaboratively. Figure 3 and Figure 4 The method can also provide Figure 5 At least a portion of the sequence of operations shown.

[0047] At 302, method 300 determines whether the engine is running (e.g., spinning and burning fuel) and whether the pressure in the fuel tank of the vehicle is greater than a threshold pressure. If so, the answer is yes and method 300 proceeds to 304. Otherwise, the answer is no and method 300 proceeds to 310.

[0048] At 304 , method 300 opens the CPV and FTIV. This allows fuel vapor to flow from the fuel tank to the engine. Method 300 proceeds to 306 .

[0049] At 306 , method 300 purges fuel vapors from the fuel tank and the carbon-filled fuel vapor storage canister to the engine where the fuel vapors are combusted. Method 300 returns to 302 .

[0050] At 310, method 300 determines if there is a request to refill the fuel tank and if the pressure in the fuel tank is greater than a threshold pressure. If so, the answer is yes and method 300 proceeds to 312. Otherwise, the answer is no and method 300 proceeds to 320. In one example, a user may press a button to indicate a request for refueling and open the fuel access door and reduce the pressure in the fuel tank. Pressure may build up in the fuel tank due to diurnal heating of the fuel.

[0051] At 312 , method 300 activates the EHC and brings the EHC to operating temperature such that the EHC can combust hydrocarbons. Method 300 proceeds to 314 .

[0052] At 314, method 300 closes the FTIV and opens the FRPRV in response to the temperature of the electrically heated catalyst exceeding a threshold temperature. Thus, method 300 can hold the fuel vapors in the fuel tank until the electrically heated catalyst reaches operating temperature. Once the electrically heated catalyst reaches operating temperature, the fuel vapors are released to the electrically heated catalyst where they can combust. Method 300 proceeds to 316.

[0053] At 316 , method 300 judges whether the pressure in the fuel tank is less than a threshold pressure. If method 300 judges that the pressure in the fuel tank is less than a threshold pressure, the answer is yes and method 300 proceeds to 316 . Otherwise, the answer is no and method 300 returns to 312 .

[0054] At 318 , method 300 closes the FRPRV. Method 300 proceeds to exit.

[0055] Steering Figure 4At 320, method 300 judges whether the engine is off (e.g., not rotating and not burning fuel). If method 300 judges that the engine is off, the answer is yes and method 300 proceeds to 320. Otherwise, the answer is no and method 300 proceeds to exit.

[0056] At 322, method 300 judges whether evaporative emissions system diagnostics are requested. In one example, evaporative emissions diagnostics may be performed at a predetermined operating time or after the vehicle has traveled a predetermined distance. If method 300 judges that evaporative emissions diagnostics are requested, the answer is yes and method 300 proceeds to 324. Otherwise, the answer is no and method 300 proceeds to 324.

[0057] At 324, method 300 performs a breach test to determine whether air can flow into or out of the evaporative emissions system at a rate above a predetermined rate when the valve of the evaporative emissions system is positioned to reduce airflow into and out of the evaporative emissions system. In one example, method 300 may close the CPV, close the FRPRV, open the FTIV, close the canister vent valve (not shown), and activate the vacuum pump to reduce the pressure within the evaporative emissions system. Once the vacuum in the evaporative emissions system is greater than a threshold amount, the vacuum pump is deactivated. If the vacuum in the evaporative emissions system is greater than a threshold amount after the vacuum pump is deactivated for a predetermined amount of time, method 300 may determine that there is no breach. Otherwise, method 300 may determine that there is a breach. If method 300 determines that the evaporative emissions system is not without a breach, the answer is no and method 300 proceeds to 350. If method 300 determines that the evaporative emissions system is not without a breach, the answer is yes and method 300 proceeds to 328. The breach test is performed when the engine is off.

[0058] At 350, method 300 may indicate a breach of the evaporative emissions system via displaying a message on a human / machine interface. Method 300 may also indicate the breach to a cloud server or other external device. Method 300 proceeds to exit.

[0059] At 328, method 300 opens the FTIV and opens the FRPVR. Additionally, the engine may be rotated via the electric machine and the exhaust poppet valves and / or intake poppet valves of the engine are closed and maintained closed to seal the cylinders of the engine closed. The FTIV is opened and the FRPVR is opened to allow flow from the exhaust system of the engine through the evaporative emission system and out to the atmosphere. A carbon filled fuel vapor storage canister may capture fuel vapors flowing through the evaporative emission system. Method 300 proceeds to 330.

[0060] At 330 , if the FRPVR is commanded open, method 300 activates the vacuum pump 296 in the ELCM and draws gas from the exhaust system of the engine through the evaporative emissions system. Method 300 proceeds to 332 .

[0061] At 332, method 300 determines whether the gas flow through a gasoline particulate filter (GPF) is greater than a predetermined flow and whether the pressure in the fuel tank has dropped to less than a threshold pressure amount. The flow through the GPF may be indicated by a differential pressure sensor. If method 300 determines that the flow through the GPF is greater than a first threshold amount and the pressure in the fuel tank has dropped more than a second threshold amount after vacuum pump 296 is activated, the answer is yes and method 300 proceeds to 334. If method 300 determines that the flow through the GPF is less than the first threshold amount and the pressure in the fuel tank has not dropped more than a second threshold amount after vacuum pump 296 is activated, the answer is no and method 300 proceeds to 360.

[0062] At 360 , the method 300 indicates that the FRPVR is stuck in the closed position. The method 300 may publish a message regarding FRPVR degradation to a human / machine interface or an external device (eg, a cloud server). The method 300 proceeds to 362 .

[0063] At 362 , method 300 commands the FTIV to close and the FRPVR to close. The valves may be closed to prevent the FRPVR from accidentally opening. Method 300 proceeds to 364 .

[0064] At 364 , method 300 deactivates the vacuum pump of the ELCM. Method 300 proceeds to exit.

[0065] At 334 , the method 300 indicates that the FRPVR is operating as expected. The indication may be provided to a human-machine interface and / or a cloud server. The method 300 proceeds to 336 .

[0066] At 336 , method 300 maintains the FTIV in an open position and closes the FRPVR. The FTIV is commanded to remain open so that the vacuum pump can draw gas upstream of the FTIV. Method 300 proceeds to 338 .

[0067] At 338, method 300 judges whether the gas flow through the GPF has stopped at less than a threshold flow rate for less than a predetermined amount of time. If so, the answer is yes and method 300 proceeds to 370. Otherwise, the answer is no and method 300 proceeds to 340.

[0068] At 370, the method 300 indicates that the FRPVR is operating as might be expected. The method 300 proceeds to 342. The indication may be made via a human-machine interface or a remote cloud server.

[0069] At 340, the method 300 indicates that the FRPVR is not operating as might be expected. The method 300 proceeds to 342. The indication may be made via a human-machine interface or a remote cloud server.

[0070] At 342 , method 300 commands the FTIV to be closed and the FRPVR to be closed. Method 300 also commands the ELCM vacuum pump to be closed. Method 300 proceeds to exit.

[0071] In this way, Figure 3 and Figure 4 A method for an engine may be provided, the method comprising: activating a pump and commanding a fuel refilling pressure relief valve to open in response to a request to diagnose a fuel refilling pressure relief valve, the fuel refilling pressure relief valve being positioned along a first passage between an engine exhaust system and a fuel tank. In a first example, the method further comprises opening a fuel tank isolation valve in response to a request to diagnose the fuel refilling pressure relief valve. In a second example, which may include the first example, the method further comprises monitoring a flow through an exhaust device. In a third example, which may include one or both of the first and second examples, the method comprises: wherein the pump is positioned along a second passage between a carbon-filled canister and an atmospheric opening. In a fourth example, which may include one or more of the first to third examples, the method further comprises indicating degradation of the fuel refilling pressure relief valve in response to a flow rate less than a threshold flow rate. In a fifth example, which may include one or more of the first to fourth examples, the method further comprises indicating that there is no degradation in response to a flow rate greater than a threshold flow rate. In a sixth example, which may include one or more of the first to fifth examples, the method further comprises closing or keeping closed all exhaust valves of the engine in response to a request to diagnose the fuel refilling pressure relief valve.

[0072] Figure 3 and Figure 4 The method also provides a method for an engine, the method comprising: closing an exhaust valve of the engine and activating a pump in response to a request to diagnose a fuel refilling pressure relief valve, the fuel refilling pressure relief valve being positioned along a first passage between an exhaust system of the engine and a fuel tank. In a first example, the method further comprises monitoring flow through the exhaust system in response to a request to diagnose the fuel refilling pressure relief valve. In a second example, which may include the first example, the method comprises: wherein the engine does not burn fuel and air. In a third example, which may include one or both of the first and second examples, the method further comprises commanding the opening of a fuel tank isolation valve. In a fourth example, which may include one or more of the first to third examples, the method comprises: wherein the fuel tank isolation valve is positioned along a second passage, the second passage extending between a carbon-filled canister and the fuel tank.

[0073] Reference now Figure 5 , showing that according to Figure 1 and Figure 2 systems and Figure 3 and Figure 4An exemplary sequence of operations of the method. Figure 1 and Figure 2 system and Figure 3 and Figure 4 Collaboration to provide Figure 5 The vertical lines at times t0-t4 represent times of interest during the sequence of operations. The graphs are aligned in time.

[0074] from Figure 5 The first graph from the top of is a graph of the FRPRV diagnostic status versus time. The vertical axis represents the FRPRV diagnostic status, and when trace 502 is near the horizontal axis, the FRPRV diagnostic status indicates that no diagnostics are performed. When trace 502 is near the vertical axis arrow, a diagnosis is requested. The horizontal axis represents time, and time increases from the left side of the graph to the right side of the graph. Trace 502 represents the FRPRV diagnostic status.

[0075] from Figure 5 The second graph from the top is a graph of the FRPRV command status versus time. The vertical axis represents the FRPRV command status, and when trace 504 is near the horizontal axis, the FRPRV command status indicates that no command to open the FRPRV has been issued. When trace 504 is near the vertical axis arrow, a command to open the FRPRV has been issued. The horizontal axis represents time, and time increases from the left side of the graph to the right side of the graph. Trace 504 represents the FRPRV command status.

[0076] from Figure 5 The third graph from the top of is a graph of FTIV command status versus time. The vertical axis represents the FTIV command status, and when trace 506 is near the horizontal axis, the FTIV command status indicates that no command to open the FTIV has been issued. When trace 506 is near the vertical axis arrow, a command to open the FTIV has been issued. The horizontal axis represents time, and time increases from the left side of the graph to the right side of the graph. Trace 506 represents the FTIV command status.

[0077] from Figure 5 The fourth graph from the top of is a graph of vacuum pump command status versus time. The vertical axis represents the vacuum pump command status, and when trace 508 is near the horizontal axis, the vacuum pump command status indicates that the vacuum pump is not commanded to be activated. When trace 508 is near the vertical axis arrow, the vacuum pump is commanded to be on. The horizontal axis represents time, and time increases from the left side of the graph to the right side of the graph. Trace 508 represents the vacuum pump command status.

[0078] from Figure 5The fifth graph from the top of FIG. 5 is a graph of flow through the GPF versus time. The vertical axis represents GPF flow, and GPF flow increases in the direction of the vertical axis arrow. The horizontal axis represents time, and time increases from the left side of the graph to the right side of the graph. Trace 510 represents flow through the GPF.

[0079] from Figure 5 The sixth graph from the top of is a graph of FRPRV degradation status versus time. The vertical axis represents the FRPRV degradation status, and when trace 512 is near the horizontal axis, the FRPRV degradation status indicates that there is no degradation. When trace 512 is near the vertical axis arrow, degradation is indicated. The horizontal axis represents time, and time increases from the left side of the graph to the right side of the graph. Trace 512 represents the FRPRV degradation status.

[0080] At time t0, the FRPRV diagnostic is not activated and the FRPRV is not commanded open. Additionally, the FTIV is not commanded open and the vacuum pump is not activated. Flow through the GPF is zero and no FRPRV degradation is indicated.

[0081] At time t2, the FRPRV diagnostic is activated and the FRPRV is commanded open. Additionally, the FTIV is commanded open and the vacuum pump is activated. Flow through the GPF remains at zero and no FRPRV degradation is indicated.

[0082] At time t3, the FRPRV diagnostic remains activated and the FRPRV is commanded open. Additionally, the FTIV remains commanded open and the vacuum pump remains activated. However, flow through the GPF remains zero, thus now indicating FRPRV degradation because a threshold amount of time has passed since the valve opened and the vacuum pump was activated.

[0083] At time t4, the FRPRV diagnostic is disabled and FRPRV degradation is indicated. The FRPRV is commanded closed, and the FTIV is commanded closed. Additionally, the vacuum pump is commanded disabled. Flow through the GPF remains near zero.

[0084] In this way, the FRPRV may be selectively opened to release fuel vapor from the fuel tank and / or a carbon-filled fuel vapor storage canister to an electrically heated catalyst to combust the fuel vapor in a vehicle that may not have an internal engine that is frequently started. The opening and closing of the FRPRV may be evaluated upon command.

[0085] It should be noted that the exemplary control and estimation procedures included herein can be used with various engine and / or vehicle system configurations. The control methods and procedures disclosed herein can be stored as executable instructions in a non-transitory memory and can be executed by a control system including a controller in combination with various sensors, actuators and other engine hardware. The specific routines described herein may represent one or more of any number of processing strategies (such as event-driven, interrupt-driven, multi-tasking, multi-threading, etc.). To this end, the various actions, operations and / or functions shown may be executed in the sequence described, executed in parallel, or omitted in some cases. Similarly, the processing order is not necessarily required to achieve the features and advantages of the example embodiments described herein, but is provided for ease of illustration and description. One or more of the actions, operations and / or functions shown may be repeatedly performed according to the specific strategy used. In addition, the described actions, operations and / or functions may graphically represent the code in the non-transitory memory of a computer-readable storage medium that will be programmed into the engine control system, wherein the described actions are implemented by executing instructions in a system including various engine hardware components in conjunction with an electronic controller.

[0086] It should be understood that the configurations and procedures disclosed herein are exemplary in nature, and these specific embodiments should not be considered to be limiting, as many variations are possible. For example, the above technology can be applied to V-6 cylinders, inline 4 cylinders, inline 6 cylinders, V-12 cylinders, opposed 4 cylinders, and other engine types. In addition, unless explicitly stated to the contrary, the terms "first", "second", "third", etc. are not intended to represent any order, position, quantity, or importance, but are only used as marks to distinguish one element from another. The subject matter of the present disclosure includes all novel and non-obvious combinations and sub-combinations of the various systems and configurations and other features, functions, and / or properties disclosed herein.

[0087] As used herein, unless otherwise specified, the term "about" is interpreted to mean ±5% of the stated range.

[0088] The appended claims particularly point out certain combinations and subcombinations regarded as novel and non-obvious. These claims may refer to "an" element or "a first" element or the equivalent thereof. Such claims may be understood to include incorporation of one or more such elements, neither requiring nor excluding two or more such elements. Other combinations and subcombinations of the disclosed features, functions, elements, and / or properties may be claimed by amendment of the present claims or by presentation of new claims in this or a related application. Such claims, whether broader, narrower, equal, or different in scope to the original claims, are also deemed to be included in the subject matter of the present disclosure.

[0089] According to the present invention, a method for an engine includes activating a pump and commanding opening of a fuel refill pressure relief valve in response to a request to diagnose a fuel refill pressure relief valve located along a first passage between an engine exhaust system and a fuel tank.

[0090] In one aspect of the present invention, the method includes opening a fuel tank isolation valve in response to a request to diagnose a fuel refill pressure relief valve.

[0091] In one aspect of the invention, the method includes monitoring flow through the discharge device.

[0092] In one aspect of the invention, the pump is positioned along the second passage between the carbon filled canister and the atmosphere opening.

[0093] In one aspect of the present invention, the method includes indicating fuel refill pressure relief valve degradation in response to a flow rate being less than a threshold flow rate.

[0094] In one aspect of the invention, the method includes indicating an absence of degradation in response to the flow rate being greater than a threshold flow rate.

[0095] In one aspect of the invention, the method includes closing or maintaining closed all exhaust valves of the engine in response to a request to diagnose the fuel refill pressure relief valve.

[0096] According to the present invention, a system for a vehicle is provided, comprising: an internal combustion engine, the internal combustion engine including an exhaust system; a fuel tank; an evaporative emission system, the evaporative emission system including a pump and a fuel refill pressure relief valve, the fuel refill pressure relief valve being positioned along a first passage extending between the fuel tank and the exhaust system; and a controller, the controller including executable instructions stored in a non-transitory memory, the executable instructions causing the controller to diagnose the fuel refill pressure relief valve via activating the pump.

[0097] According to one embodiment, the invention also features additional executable instructions that cause the controller to monitor flow through the fuel refill pressure relief valve.

[0098] According to one embodiment, the invention also features a differential pressure sensor.

[0099] According to one embodiment, flow through the fuel refill pressure relief valve is monitored via a differential pressure sensor.

[0100] According to one embodiment, a differential pressure sensor is configured to sense pressure across the particulate filter.

[0101] According to one embodiment, the invention also features additional executable instructions that cause the controller to command opening of the fuel refill pressure relief valve to diagnose the fuel refill pressure relief valve.

[0102] According to one embodiment, the invention also features a fuel tank isolation valve and additional executable instructions for commanding opening of the fuel tank isolation valve to diagnose a fuel refill pressure relief valve.

[0103] According to one embodiment, activating the pump causes gas to be drawn from the exhaust system to the pump.

[0104] According to the present invention, a method for an engine includes closing an exhaust valve of the engine and activating a pump in response to a request to diagnose a fuel refill relief valve located along a first passage between an engine exhaust system and a fuel tank.

[0105] In one aspect of the invention, the method includes monitoring flow through the exhaust device in response to a request to diagnose a fuel refill pressure relief valve.

[0106] In one aspect of the invention, the engine does not combust fuel and air.

[0107] In one aspect of the invention, the method includes commanding opening of a fuel tank isolation valve.

[0108] In one aspect of the present invention, the fuel tank isolation valve is positioned along a second passage extending between the carbon filled canister and the fuel tank.

Claims

1. A method for an engine, comprising: A pump is activated and commanded to open in response to a request to diagnose a fuel refill pressure relief valve located along a first passage between an engine exhaust system and a fuel tank. 2 . The method of claim 1 , further comprising opening a fuel tank isolation valve in response to the request to diagnose the fuel refill pressure relief valve.

3. The method of claim 2, further comprising monitoring flow through the discharge device.

4. The method of claim 3, wherein the pump is positioned along a second passage between the carbon filled canister and an atmosphere opening. 5 . The method of claim 4 , further comprising indicating degradation of the fuel refill pressure relief valve in response to the flow rate being less than a threshold flow rate. 6 . The method of claim 5 , further comprising indicating an absence of degradation in response to the flow rate being greater than the threshold flow rate.

7. The method of claim 6 further comprising closing or maintaining closed all exhaust valves of the engine in response to the request to diagnose the fuel refill pressure relief valve.

8. A system for a vehicle, comprising: an internal combustion engine, the internal combustion engine comprising an exhaust system; Fuel tank; an evaporative emissions system including a pump and a fuel refill pressure relief valve positioned along a first passage extending between the fuel tank and the exhaust system; as well as A controller including executable instructions stored in non-transitory memory that cause the controller to diagnose the fuel refill pressure relief valve via activating the pump.

9. The system of claim 8, further comprising additional executable instructions for causing the controller to monitor flow through the fuel refill pressure relief valve.

10. The system of claim 9, further comprising a differential pressure sensor.

11. The system of claim 10, wherein flow through the fuel refill pressure relief valve is monitored via the differential pressure sensor.

12. The system of claim 11, wherein the differential pressure sensor is configured to sense pressure across a particulate filter.

13. The system of claim 12 further comprising additional executable instructions causing the controller to command opening of the fuel refill pressure relief valve to diagnose the fuel refill pressure relief valve.

14. The system of claim 13 further comprising a fuel tank isolation valve and additional executable instructions for commanding opening of the fuel tank isolation valve to diagnose the fuel refill pressure relief valve.

15. The system of claim 14, wherein activating the pump causes gas to be drawn from the exhaust system to the pump.

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