Abstract: A fuel system is disclosed for use with an engine. The fuel system may have a plurality of fuel injectors, a common rail fluidly, a pump, and an outlet valve associated with the pump. The fuel system may also have a sensor configured to generate a signal indicative of a pressure of fuel in the common rail, and an electronic control module. The electronic control module may be configured to detect a zero-fueling condition, to determine a first pressure decay rate of the common rail during the zero-fueling condition while the pump is rotating, and to determine a second pressure decay rate of the common rail during the zero-fueling condition after the pump has stopped rotating. The electronic control module may also be configured to selectively generate a diagnostic flag associated with wear of the outlet valve based on the first and second pressure decay rates.

Abstract: A fuel system is disclosed for use with an engine. The fuel system may have a plurality of fuel injectors, a common rail fluidly, a pump, and an outlet valve associated with the pump. The fuel system may also have a sensor configured to generate a signal indicative of a pressure of fuel in the common rail, and an electronic control module. The electronic control module may be configured to detect a zero-fueling condition, to determine a first pressure decay rate of the common rail during the zero-fueling condition while the pump is rotating, and to determine a second pressure decay rate of the common rail during the zero-fueling condition after the pump has stopped rotating. The electronic control module may also be configured to selectively generate a diagnostic flag associated with wear of the outlet valve based on the first and second pressure decay rates.