Methods and systems are provided for improving the efficiency of canister purge completion. Based on engine operating conditions, a canister is purged to a compressor inlet or a throttle outlet. During purging conditions, as canister loads change, a purge flow through the canister is varied so that a fixed preselected portion of total engine fueling is delivered as fuel vapors.

Methods and systems are provided for controlling canister purge flow in a boosted engine. An example method for the boosted engine comprises, during boosted conditions, flowing stored fuel vapors from a canister into an ejector coupled in a compressor bypass passage, the flowing bypassing a canister purge valve. The method further comprises, responsive to a canister load higher than a threshold load, closing a canister vent valve coupled to the canister, and discontinuing flowing stored fuel vapors from the canister into the ejector.

In a vaporized fuel processing apparatus in which fuel vapor within a fuel tank is adsorbed by a canister, the adsorbed vaporized fuel is drawn to an engine, a closing valve is provided connecting the fuel tank and the canister for controlling communication between the fuel tank and the canister, and a purge valve is provided connecting the canister and the engine for controlling communication between the canister and the engine. The vaporized fuel processing apparatus includes an internal pressure sensor configured to detect a pressure of a space within the fuel tank as an internal pressure, and a closing valve control means configured to open the closing valve for supplying an atmospheric pressure to the fuel tank via the canister when the sensor detects that the internal pressure of the fuel tank is negative, while the purge valve is closed. Therefore, the air/fuel ratio is prevented from being disturbed.

An evaporated fuel processing device configured to adsorb evaporated fuel in a fuel tank to a canister and to feed the adsorbed evaporated fuel to an engine. The device includes an inner pressure sensor configured to detect a pressure in an interior space of the fuel tank, a valve-opening start position determination means configured to change the stroke amount of a flow control valve from an initial condition and to determine a valve-opening start position of the flow control valve based on a requirement that a range of variation of the inner pressure is equal to or greater than a predetermined value, a learning means configured to store the valve-opening start position, and a prohibition means configured to prohibit the valve-opening start position determination means from determining the valve-opening start position when the inner pressure falls within a predetermined pressure range relative to the atmospheric pressure.

An evaporated fuel processing device utilizing a flow rate control valve as a valve positioned in a passage connecting a fuel tank with a canister. The device includes: a valve opening means for opening the flow rate control valve at a constant speed; an internal pressure sensor; a valve opening start position detecting means for acquiring a second derivative value of the internal pressure after a valve opening motion of the flow rate control valve has started and for detecting a valve opening start position of the flow rate control valve based on the second derivative value; a learning means for storing the valve opening start position; and a valve opening speed change means for changing a valve opening speed of the valve opening means based on a variation speed of the internal pressure before the valve opening motion of the flow rate control valve has started.

A purge device includes a canister; a purge passage configured to extend from the canister and be connected to an upstream side of a compressor of a supercharger in an intake passage; a supply unit configured to supply purge gas to the upstream side of the compressor in the intake passage during supercharging; a throttle configured to be provided in a portion of the intake passage connected with the purge passage and limit an inflow of gas from the purge passage; a sensor configured to detect internal pressure downstream of the supply unit in the purge passage; and a control device configured to determine that a passage end of the purge passage deviates from the intake passage, in a case where a detection value obtained by the sensor during the operation of the supply unit is lower than a predetermined pressure.

Methods and systems are presented for diagnosing operation of passive grade vent valves of a fuel system. The methods and systems include adjusting a position of a vehicle so that fuel in a fuel tank may cause a first grade vent valve to open and a second grade vent valve to close.

A system according to the present disclosure includes a pump operating parameter module and a purge flow control module. The pump operating parameter module determines a value of an operating parameter of a purge pump that delivers purge fluid from a canister in an evaporative emissions system to an intake system of an engine. The operating parameter of the purge pump includes at least one of a speed of the purge pump, an amount of current supplied to the purge pump, and an amount of power supplied to the purge pump. The purge flow control module controls at least one of a purge valve and the purge pump to adjust an amount of purge fluid delivered to a cylinder of an engine based on the determined value of the operating parameter of the purge pump.

A fuel vapor processing apparatus may include a canister. A negative pressure applying device for applying a negative pressure to the canister may be disposed in a purge passage communicating between the canister and an intake pipe of an engine. A pressure adjusting device may be disposed in a portion of the purge passage communicating between the fuel tank and the negative pressure applying device.

A fuel vapor processing apparatus includes a canister housing an adsorbent material that adsorbs fuel vapor from a tank, and a valve in a passage connecting the canister and tank. When a stroke amount is within a range, the valve is closed to close the tank and a valve opening start position is learned. In the learning, the stroke amount is varied in the opening direction by repeatedly changing in the opening direction by a first stroke and maintaining for a first time period, and subsequently changing in a closing direction by a second stroke and maintaining for a second time period. The valve opening start position is determined based on the stroke amount in the second time period when the tank pressure is reduced by the predetermined value or more or in a preceding process.