Systems for hybrid electric engines have a fuel vapor canister (FVC) in fluid communication with (i) fuel vapor in a fuel tank with a refueling valve therebetween, (ii) an intake manifold with a canister purge valve therebetween, and (iii) atmospheric pressure (atm) with a canister vent valve (CVV) therebetween, a bypass loop around the refueling valve, and a pressure sensor upstream of both the refueling valve and the CVV. The loop has a control pump and a control valve controlling fluid communication with atm, and in a first mode, control valve and CVV open, pumps fuel vapor to the FVC for pressure control, then closes the control valve; in a second mode, control valve closed and CVV open, pumps atm to the FVC; and in a third mode, control valve and CVV open, pumps fuel vapor to the FVC to a pre-selected threshold to close the CVV.

A leak detection module (LDM) includes a housing, a canister valve solenoid (CVS) that is arranged within the housing and in fluid communication along a first fluid passageway between first and second ports. The module also includes a pump that is arranged within the housing and is in fluid communication with the first and second ports, and a pressure sensor that is in fluid communication with at least one of the first and second ports. A first controller is arranged in the housing and is in communication with the pump, the CVS and the pressure sensor. The first controller runs a test procedure using the pump and operating the CVS between open and closed positions to monitor a pressure within the module. The first controller communicates a result based upon the monitored pressure to a second controller that is arranged outside the housing and remotely from the module.

A leakage detector for a fuel vapor processing system having a canister. The leakage detector includes a sealing system and a control unit. The sealing system is connected to the canister and is configured to sealingly close an inspection area, which includes the canister. The control unit is implemented by at least one programmed processor. The control unit is configured to calculate an amount of fuel vapor in the canister. The control unit is also configured to select a leakage detection method from the group consisting of a positive pressure type and a negative pressure type. The selection is made based on the calculated amount of the fuel vapor in the canister. The control unit is further configured to perform the leakage detection method in response to temporal changes in an internal pressure of the inspection area closed by the sealing system.

Methods and systems are provided for an evaporative emissions control system for onboard refueling vapor recovery of a heavy duty vehicle. In one example, a method may include adjusting flow among at least two canisters during canister purging, where the at least two canisters are arranged in a parallel loading and unloading flow direction, to increase flow through a higher loaded canister. Flow may be adjusted using a first valve coupled to the first canister, a second valve coupled to the second canister, and so on for n number of canisters and n number of valves, and a balancing valve used to selectively couple the at least two canisters to a fuel tank.

Methods and systems are provided for diagnosing degradation and/or alteration in an evaporative emission control system of a vehicle. In one example, a method for a vehicle may comprise, during a refueling event, detecting presence or absence of a fuel vapor canister coupled to a vent line of the evaporative emission control system of the vehicle based on a response of a hydrocarbon sensor coupled to the vent line. In this way, hydrocarbon emissions may be reduced by identifying vehicles with tampered or degraded evaporative emission control system.

A failure diagnostic device is configured to determine saturated vapor pressures of a fuel within a fuel tank. In a fuel vapor processing apparatus, some or all of the passages and spaces into which the fuel vapor flows into the fuel vapor processing apparatus are closed to the atmosphere. In this condition, the failure diagnostic device determines a plurality of saturated vapor pressure characteristics over time. The failure diagnostic device is configured to diagnose whether or not a leakage or a blockage failure in the fuel vapor processing apparatus is present. The failure diagnostic device determines a Reid vapor pressure (RVP) based on each of the plurality of determined saturated fuel vapor pressure characteristic and diagnoses whether or not a failure is present in accordance with a change in these RVPs over time.

A pressure sensor for an evaporated fuel leak detector is used for checking a leak in a fuel tank and a canister. The pressure sensor includes a sensor unit, a case, and a sealing resin. The sensor unit includes a pressure receiving portion for detecting a pressure of a fluid applied to a pressure receiving surface, and a mold resin portion covering a surface of the pressure receiving portion except for the pressure receiving surface. The case has a fluid flow path for introducing the fluid to the pressure receiving surface, and a housing recess in which the sensor unit is accommodated. The sealing resin is arranged in the housing recess, to at least cover a back surface of the mold resin portion located on an opposite side of the pressure receiving surface.

A fault diagnosis method is provided for an evaporated fuel processing device including a canister including a charge port connected to an upper space of a fuel tank, a purge passage connecting a purge port of the canister and an intake system, and including a purge control valve, a drain passage including a drain cut valve, and a pressure sensor. The pressure sensor is configured to sense, as a purge passage pressure, a pressure between the purge control valve and the canister in the purge passage. The fault diagnosis method includes performing a purge by opening the purge control valve in a state in which the drain cut valve is controlled to be opened; measuring an actual pressure variation by the pressure sensor; and diagnosing a closing fixation of the drain cut valve by comparing a predetermined pressure variation and the actual pressure variation.

A controller is configured to execute an emission process of, on condition that the number of times a leakage diagnosis of a fuel tank is performed in a stop period from when an internal combustion engine stops to when the engine restarts is less than a predetermined allowable number of times, emitting gas from the fuel tank via a canister by opening a shut-off valve, execute a diagnosis process of performing the leakage diagnosis based on a change in index value, caused by the emission process, the index value indicating a pressure in the fuel tank, and execute a subtraction process of, when fuel has been fed to the fuel tank in a state where the shut-off valve is open in the stop period of the internal combustion engine, reducing the allowable number of times in the stop period in which fuel has been fed to the fuel tank.

A leakage diagnostic device diagnoses leakage of evaporated fuel in an evaporative fuel treatment device. The evaporative fuel treatment device purges evaporated fuel, which is generated in a fuel tank and adsorbed on a canister, to an intake passage. The leakage diagnostic device includes a vent valve that blocks a first atmospheric passage, which connects the canister with an atmospheric opening, and a pump that pressurizes and depressurizes a second atmospheric passage, which is a bypass passage of the first atmospheric passage. The malfunction diagnostic device diagnoses malfunction of the leakage diagnostic device based on an output value of a pressure sensor that detects pressure in a passage connected to the canister.