Methods and systems are provided for calculating a fuel aging of fuel in a fuel tank. In one example, a method may include alerting a vehicle operator and/or adjusting engine operating parameters in response to a fuel aging being greater than a threshold aging.

A diagnostic system for a fuel injector includes a plurality of sensors to sense vehicle data. A controller includes a fuel injector diagnostic module configured to receive the vehicle data during operation of the vehicle and to selectively identify at least one of a fuel injector with a stuck armature and a fuel injector with pintle fatigue.

A diagnostic system for a fuel injector includes a plurality of sensors to sense vehicle data. A controller includes a fuel injector diagnostic module configured to receive the vehicle data during operation of the vehicle and to selectively identify at least one of a fuel injector with a stuck armature and a fuel injector with pintle fatigue.

A fuel injection apparatus for injecting fuel to an engine having cylinders, includes: injectors corresponding to the cylinders; a regulator for fuel pressure supplied to the injectors; and a processor. The processor performs: deciding to start a deposit removal for removing deposits adhering to injector-nozzles; and controlling each injector to inject fuel in a single injection mode for injecting one time or a divided injection mode for injecting multiple times in one combustion cycle and control the regulator based on engine operation condition. The controlling includes, when controlling each injector to inject fuel in the divided injection mode based on the engine operation condition, sequentially controlling each injector to reduce injection number in one combustion cycle when the deposit removal is decided to be started, and then controlling the regulator to increase fuel pressure.

A pump life prediction system and methods for predicting pump life of a pump are disclosed. A method may include monitoring pump operating conditions. A value indicative of cavitation damage is determined based on the pump operating conditions. A pump life remaining is determined based on the value. The method may also include outputting an indication of the pump life remaining.

Methods and systems for supply of fuel for a turbine-driven fracturing pump system used in hydraulic fracturing may be configured to identify when the supply pressure of primary fuel to a plurality of gas turbine engines of a plurality of hydraulic fracturing units falls below a set point, identify a gas turbine engine of the fleet of hydraulic fracturing units operating on primary fuel with highest amount of secondary fuel available, and to selectively transfer the gas turbine engine operating on primary fuel with the highest amount of secondary fuel from primary fuel operation to secondary fuel operation. Some methods and systems may be configured to transfer all gas turbine engines to secondary fuel operation and individually and/or sequentially restore operation to primary fuel operation and/or to manage primary fuel operation and/or secondary fuel operation for portions of the plurality of gas turbine engines.

Methods and systems are provided for conducting a fuel tank diagnostic. In one example, a method comprises sealing a fuel tank of a vehicle, retrieving data related to fuel tank pressure from a crowd of vehicles, and indicating the fuel tank of the vehicle being diagnosed is degraded responsive to data related to fuel tank pressure from the crowd insufficiently correlating with a set of data related to fuel tank pressure from the vehicle. In this way, fuel tank degradation may be indicated without coupling the fuel tank of the vehicle to atmosphere, which may reduce a release of undesired evaporative emissions to atmosphere.

Various methods and systems are provided for diagnosing a condition of a fuel injector of an engine. In one example, a method for an engine includes injecting a first pulse of fuel as a first pilot injection into a first subset of cylinders of a plurality of engine cylinders, where the first pilot injection precedes a primary injection of fuel into the first subset of cylinders by a duration; correlating a first response in an engine operating parameter to the first pilot injection; and adjusting the primary injection of fuel into the first subset of cylinders based on the first response. In one example, the first pilot injection precedes the primary injection by a predefined short duration and the primary injection of fuel is adjusted within a predefined or preset upper limit and lower limit.

An abnormality diagnosis system of an air-fuel ratio sensor acquires a blowby gas flow ratio showing a ratio of the flow of blowby gas to the flow of gas to a combustion chamber and an output current of an air-fuel ratio sensor during fuel cut control in which an internal combustion engine stops the feed of fuel to the combustion chamber and at a plurality of points of time of different flows of blowby gas passing through a blowby gas passage and flowing to the downstream side of a throttle valve in the intake passage, calculate an output current of the air-fuel ratio sensor corresponding to a blowby gas flow ratio smaller than the blowby gas flow ratios acquired at the plurality of points of time, based on the acquired blowby gas flow ratio and output current, and judge the air-fuel ratio sensor for abnormality based on the calculated output current.

A method for identifying faulty components of a fuel injection system is disclosed, wherein a secondary injection is performed individually by each injector during a test routine, after the secondary injection several predefined parameters of the fuel injection system are determined, and a combined assessment of the determined parameters is used to draw conclusions about whether or not components of the fuel injection system are faulty.