A pump unit may include a pump configured to increase a pressure of diesel fuel and discharge the diesel fuel to a fuel passage in which a filter is disposed, and a controller configured to control an operation of the pump. The controller may be configured to execute freeze avoidance control in which the operation of the pump is controlled using an index that indicates a degree of clogging of the filter caused by the diesel fuel freezing. In the freeze avoidance control, the controller may be configured to apply a higher load to the pump as the degree of clogging of the filter indicated by the index is higher.

A dual-chamber electrolysis vessel safely stores HHO gas for use by an internal combustion engine.

A method for determining the presence of water and diesel exhaust fluid mixed with diesel fuel is disclosed. In one example, output pressure of a fuel pump may be indicative of the presence or absence of water in diesel fuel. The presence or absence of water in fuel may be evaluated in response to filling a fuel tank.

A vehicle and a fuel system for a vehicle are provided. The fuel system has a fuel tank, a fuel fill inlet fluidly connected to the fuel tank to receive fuel dispensed from an external fuel supply device, and a recirculation line with a first end fluidly connected to the fuel fill inlet and a second end fluidly connected to the fuel tank. An ejector is positioned within the recirculation line. A valve fluidly connects the ejector to the fuel tank via a drain line. A method of fueling a vehicle is also provided.

A concentration measuring device includes a circulation passage, an aspirator, a differential pressure sensor, and a control unit. The aspirator is disposed in a fuel tank and is connected to the circulation passage. While a gas flows from a gaseous layer within a fuel tank through the circulation passage due to a negative pressure generated in the aspirator, the differential pressure sensor measures a pressure difference of the gas within the circulation passage between an upstream side of a narrowed part, having a narrower passage area than an adjacent portion of the circulation passage, and a downstream side of the narrowed part. The control unit is configured to calculate a density of the fuel vapor from the pressure difference of the gas and to calculate a concentration of the fuel vapor from the density of the fuel vapor.

A fuel supply system includes an electronic control unit that outputs a target fuel pressure for controlling a low-pressure pump and an engine status, and a fuel pump controller (FPC) that generates a drive signal for driving the low-pressure pump based on the target fuel pressure. The FPC is configured to obtain an actual fuel pressure, to set a duty ratio and to perform a feedback control for the actual fuel pressure to follow the target fuel pressure, and to set a lower limit guard value based on the engine status. The lower limit guard setter sets a duty ratio of 0% as the lower limit guard value when the engine status indicates a stop of the engine.

A method of controlling an engine system includes controlling a fuel injector to perform a zero-fueling injector operation during operation of the engine, the zero-fueling injector operation including a non-zero injector on-time resulting in zero fueling by the injector, determining an injection system pressure change associated with the zero-fueling injector operation, modifying at least one fuel injection control parameter in response to the injection system pressure change, and using the modified fuel injection control parameter to control injection of fuel by the fuel injector during operation of the engine.

Methods and systems are provided for diagnosing potential degradation of a fuel tank pressure sensor. In one example, a method may include, in response to an ambient pressure reading by the fuel tank pressure sensor during an evaporative emissions (EVAP) system diagnostic, applying vacuum to the EVAP system and indicating degradation of the fuel tank pressure sensor if the canister undergoes an endothermic reaction. If the fuel tank pressure sensor is determined to not be degraded, the method further includes distinguishing between the ambient pressure reading being caused by a leak in the EVAP system and a canister purge valve being stuck closed.

Embodiments disclosed herein relate generally to systems and methods of operating internal combustion (IC) engines, and more specifically to systems and methods of starting compression ignition (CI) engines when the surrounding environment is significantly colder than the normal operating temperature of the engine (i.e., “cold-starting”). In some embodiments, the CI engine can include an ignition-assist device. In some embodiments, a method of operating a CI engine during cold-start can include opening an intake valve to draw a volume of air into the combustion chamber, moving a piston from a bottom-dead-center position to a top-dead-center position in a combustion chamber at a compression ratio of between about 15 and about 25, injecting a volume of fuel, the fuel having a cetane number of less than about 30, closing the intake valve, and combusting substantially all of the volume of fuel.

A pump health assessment system and a method for providing a pump health of a pump is disclosed. The method includes: determining that there is an imbalance in the pump; increasing pump flow from the pump; measuring a rail pressure of a fuel rail; determining if the rail pressure is substantially equal to an expected rail pressure profile; and in accordance with a determination that the rail pressure is not substantially equal to the rail pressure profile, outputting an indication of pump damage.