A diagnosis device for an evaporated fuel processing device includes: a pump arranged to pressurize or depressurize a system including the fuel tank and the canister; at least one pressure sensor arranged to sense a pressure within the system; and a fuel temperature sensor arranged to sense a temperature of a fuel within the fuel tank, the diagnosis device being configured to select a first leakage diagnosis using a positive pressure or a negative pressure existing within the fuel tank, or a second leakage diagnosis using a forcible pressurization or a forcible depressurization by the pump, based on a temperature difference between a fuel temperature at a start of driving, and a fuel temperature after an end of the driving, with respect to a request of a leakage diagnosis.

Methods and systems are provided for cleaning a fuel vapor storage canister positioned in an evaporative emissions control system of a vehicle. In one example, a method comprises sealing a fuel system of the vehicle for descending an altitude change that is predicted in advance, and subsequent to the vehicle descending the altitude change, unsealing the fuel system to passively purge fuel vapors stored in the fuel vapor storage canister to a fuel tank of the vehicle. In this way, bleed through emissions from the fuel vapor storage canister may be reduced, and engine operation may be improved.

A vehicle method for gaseous fuel loss detection, including for each of a high and low pressure portion of a fuel system including a gaseous fuel, indicating degradation based on a loss of mass from the fuel system, the loss of mass based on separately tracking fuel mass in each of the portions based on respective temperatures and pressures at a first and second instance following an engine off condition. The method may utilize the respective pressures and temperatures to determine which portions of the fuel system are losing mass and further identify degradation of fuel system valves.

Methods and systems are provided for mitigating the effects of a leaky fuel injector during vehicle idle stop conditions. In one example, a method may include identifying the cylinder with a leaky fuel injector, and at or during engine shutdown, positioning the engine to a selected position based on the identified cylinder such that an exhaust valve of the identified cylinder is at least partly open.

An abnormality detection device of an internal combustion engine includes an ECU that is an abnormality detection unit detecting a leakage occurrence of a second pure pipe. When the internal combustion engine is in a supercharging operation state that a supercharger operates and the second purge pipe is closed by a second purge valve, the ECU detects the leakage occurrence of the second purge pipe based on a differential pressure between a pressure in the second purge pipe and an atmospheric pressure. In this case, the valve pressure in the second purge pipe is a pressure in the second purge pipe between the second purge valve and the intake pipe.

Methods and systems are provided for performing mitigating actions in response to detecting a fuel injector leak. In one example, a method may include in response to detecting a fuel injector leak, performing first high pressure mitigating actions including increasing a fuel rail pressure, increasing a pulse width delivered to the leaking fuel injector, and commanding fuel injection during compression stroke; in response to the first mitigating actions not reducing the leak below a threshold rate, performing second high pressure mitigating actions including increasing the fuel rail pressure, increasing the pulse width delivered to the leaking injector, and commanding fuel injection during intake stroke for a cylinder receiving fuel from the leaking injector; and in response to the second mitigating actions not reducing the leak below the threshold rate, reducing the fuel rail pressure, and commanding intake stroke fuel injection to all cylinders.

Methods and systems are provided for including a single pressure sensor in an evaporative emissions system and fuel system. In one example, a method may include measuring a differential pressure between the evaporative emissions system and the fuel system using a delta pressure sensor coupled across a fuel tank isolation valve disposed between a fuel vapor storage canister of the evaporative emissions system and a fuel tank of the fuel system. Each of the fuel tank isolation valve, the fuel system, and the evaporative emissions system may be checked for degradation using the differential pressure measured by the delta pressure sensor.

Various systems are provided for delivering fuel to an engine. In one example, a system includes a controller and a fluid system configured to maintain a fluid at a pressure downstream of a check valve. The controller may be configured to determine if a leak is present in the fluid system based on a first pressure decay rate of the fluid system, and responsive to identifying that a leak is present in the fluid system, differentiate between an internal leak and an external leak based on a leak flow rate as fluid system pressure decreases.

A method for diagnosing a purge control solenoid valve (PCSV) may include forming a negative pressure in a fuel tank, checking a pressure in the fuel tank and determining whether a target negative pressure is generated, when the target negative pressure is determined not to be formed based on a result of the determining whether the target negative pressure is generated, suspecting a stuck of the PCSV that electrically controls an inflow amount of evaporated gas from the fuel tank to an intake system of an engine, and increasing a purge amount of the PCSV.

Methods and systems are provided for conducting a diagnostic routine of the fuel vapor system using pressure generated by raising or lowering a vehicle body element such as a hood or a trunk. In one example, by utilizing lift gate cylinders coupled to the hood or trunk, during raising a hood or trunk, the fuel vapor system may be evacuated and during lowering the hood or trunk, the fuel vapor system may be pressurized. A change in vacuum or higher pressure in the fuel vapor system may be monitored over a time period to detect any undesirable evaporative emissions from the fuel vapor system.