Fuel delivery system diagnostics after shut-down

A method for operation of a fuel delivery system in an internal combustion engine having a fuel system including a lower pressure pump, a higher pressure pump fluidly coupled downstream of the lower pressure pump, and a fuel rail fluidly coupled downstream of the high pressure pump comprising:

• indicating a fuel system leak based on a fuel rail pressure response and a temperature response, the fuel rail pressure and temperature response occurring after an engine shut-down;
• and
• in response to the indication and before a subsequent engine start, the subsequent engine start occurring after the engine shut-down, activating and then deactivating the lower pressure pump;
• disabling vehicle operation if fuel rail pressure drops below a threshold value during or after the activation of the lower pressure pump;
• and
• adjusting operation of one of the pumps during the subsequent engine start if fuel rail pressure achieves at least the threshold value during or after the activation of the lower pressure pump.

A article of manufacture for controlling operation of a fuel delivery system in an internal combustion engine having a fuel system including a lower pressure pump, a higher pressure pump fluidly coupled downstream of the lower pressure pump, and a fuel rail fluidly coupled downstream of the high pressure pump, the article comprising:

• code for indicating a fuel system leak based on a plurality of concurrent fuel rail pressure and temperature measurements, at least some of the fuel rail pressure and temperature measurements taken after an engine shut-down;
• and
• code for, in response to the indication and before a subsequent engine start, the subsequent engine start occurring after the engine shut-down, activating and then deactivating the lower pressure pump;
• code for disabling vehicle operation and indicating an external leak if fuel rail pressure drops below a threshold value during or after the activation of the lower pressure pump;
• and
• code for adjusting operation of one of the pumps during the subsequent engine start and indicating an internal leak if fuel rail pressure achieves at least the threshold value during or after the activation of the lower pressure pump.

A method for operation of a fuel delivery system in an internal combustion engine having a fuel system including a lower pressure pump, a higher pressure pump fluidly coupled downstream of the lower pressure pump, a solenoid valve coupled between the higher and lower pressure pumps, and a fuel rail fluidly coupled downstream of the high pressure pump comprising:

• indicating a fuel system leak based on a fuel rail pressure response, the fuel rail pressure response occurring after an engine shut-down;
• in response to the indication and before a subsequent engine start, the subsequent engine start occurring after the engine shut-down, adjusting the solenoid valve;
• and
• differentiating whether the leak includes an internal or external leak based on fuel pressure response occurring after the solenoid valve is adjusted.