A leakage diagnosis supplement method for a failure of a vacuum pump using an active purge pump may include: determining whether or not the vacuum pump mounted on a vent line between a canister and an atmosphere fails; reverse-rotating the active purge pump mounted on a purge line connecting the canister and an intake pipe to each other; determining whether or not an absolute value of internal pressure in a fuel tank is less than a specific value; and checking a leakage in the fuel system including the canister and the fuel tank.

A leakage diagnosis device is configured to detect leakage from a fuel vapor processing apparatus based on the internal pressure thereof. The fuel vapor processing apparatus includes a fuel tank and a canister in fluid communication with each other via a vapor passage. The leakage diagnosis device includes a negative pressure generator configured to generate a negative pressure therein to move gas from the canister to the fuel tank via a bypass passage. The vapor passage has an electrically controlled closing valve and a first mechanical check valve that are arranged in parallel. The first mechanical check valve is configured to be opened without electrical control to allow the fluid flow from the fuel tank to the canister. The bypass passage has a second mechanical check valve configured to be opened without electrical control to allow the fluid flow from the canister to the fuel tank.

A device may determine whether there is a communicated point with open air between a pump and a control valve or on an opposite side to the control valve of the pump, by at least two of pressures: between the pump and the control valve in case the control valve is in a cutoff state, the switching valve is in a communication state, and the pump sends in forward direction, on an opposite side to the control valve of to the pump in case the control valve is in a communication state, the switching valve is in the cutoff state, and the pump sends in reverse direction; and between the pump and the control valve or on the opposite side to the control valve of the pump in case the valves are in the cutoff states and the pump is stopped after one of these cases.

An internal combustion engine includes a state determination device. The state determination device includes a storage device and an execution device. The execution device executes an acquisition process, and a determination process. The execution device executes a guard process of bringing an internal combustion engine state variable closer to an allowable range or a value within the allowable range when the internal combustion engine state variable acquired in the acquisition process is out of the predetermined allowable range. The execution device determines the state of the internal combustion engine based on the internal combustion engine state variable after the guard process in the subsequent determination process when the guard process is executed.

A leakage detector for a fuel vapor treatment device includes a control unit. The control unit shifts a purge control valve and a shutoff valve to a first state with the purge control valve is an opened position and the shutoff valve in a closed position, and then shifts the purge control valve and the shutoff valve to a second state with the purge control valve is a closed position and the shutoff valve in a closed position. The control unit compares a first purge passage pressure acquired from the purge passage pressure detector when the purge control valve and the shutoff valve were shifted to the second state with a second purge passage pressure acquired from the purge passage pressure detector after a lapse of a first waiting time after being shifting to the second state. This comparison is used to determine leakage in the purge passage.

Disclosed is a device for evaporating vapors of a fuel stored in a motor vehicle tank. The evaporation device includes a bypass circuit and a bypass valve configured to move between a so-called absorption position, in which the bypass valve allows the gases to flow between the tank and an absorbent filter and a so-called leak detection position, in which the bypass valve allows the gases to flow between a purge circuit and the tank via the bypass circuit.

A blockage detection device opens a purge valve in a state where a negative pressure pump is operated. The negative pressure pump is connected to a downstream side of a canister with respect to a fuel tank, and reduces pressure in a device internal space. The blockage detection device calculates gas information (volume V, for example) of the device internal space on the basis of variation of internal pressure before and after the purge valve is opened. The blockage detection device detects a blockage in a vent line using the calculated gas information.

An evaporated fuel processing apparatus preventing evaporated fuel from being discharged out of a canister when residual purge gas is made to return to the canister and processed is provided. In the apparatus, an ECU performs residual purge gas processing operation of returning the residual purge gas into the canister and processing during halt of purge control. This operation includes a residual purge gas pressure-feeding process of pressure-feeding the residual purge gas with the air into the canister by the purge pump in a state in which the atmospheric passage is shut off and the purge passage and the second bypass passages are opened and an air discharge process of discharging the air in the canister outside via the atmospheric passage by opening the atmospheric passage while the purge passage and the second bypass passage are shut off.

A leak diagnosis system using a purge pump of an active purge system is provided. The leak diagnosis system includes a canister for adsorbing an evaporated gas from a fuel tank, a purge line for connecting the canister with an intake pipe, the purge pump and a purge control solenoid valve mounted to the purge line, and an auxiliary canister and an auxiliary canister control valve mounted to the purge line and located between the intake pipe and the purge control solenoid valve.

A leakage detector includes a pressure sensor for detecting the pressure in a detecting target area of the fuel vapor treatment system and a controller. The controller measures the pressure in the detecting target area at a certain point in time. The controller then determines whether the measured pressure satisfies a condition for leakage detection by a vapor pressure device. When the controller determines that the condition is satisfied, the controller selects the vapor pressure device. When the controller determines that the condition is not satisfied, the controller predicts the change in vapor pressure at a subsequent temperature based on a saturated vapor pressure characteristic of the fuel. If it is determined the pressure in the detecting target will satisfy a predetermined condition, the controller selects a pressure application device. If it is determined that the predetermined condition will be satisfied, the controller selects the vapor pressure device.