초록 ▼

Methods and systems for fuel system leak detection are disclosed. In one example approach, a method comprises, during an engine-on condition, delivering fuel from a fuel tank to one or more cylinders of the engine while the fuel tank is sealed off from atmosphere, and indicating a leak based on pres

Methods and systems for fuel system leak detection are disclosed. In one example approach, a method comprises, during an engine-on condition, delivering fuel from a fuel tank to one or more cylinders of the engine while the fuel tank is sealed off from atmosphere, and indicating a leak based on pressure in the fuel tank. For example, a leak may be indicated in response to a pressure decrease in the fuel tank greater than an expected pressure decrease, where the expected pressure decrease is based on a fuel level in the fuel tank.

대표청구항 ▼

1. A method for a vehicle with an engine, comprising: during an engine-on condition, delivering fuel from a fuel tank to one or more cylinders of the engine while the fuel tank is sealed off from atmosphere; andindicating a leak based on pressure in the fuel tank being less than a threshold during a

1. A method for a vehicle with an engine, comprising: during an engine-on condition, delivering fuel from a fuel tank to one or more cylinders of the engine while the fuel tank is sealed off from atmosphere; andindicating a leak based on pressure in the fuel tank being less than a threshold during an engine-on event where the engine-on event is subsequent to an engine-off condition following the engine-on condition. 2. The method of claim 1, further comprising indicating a leak in response to a pressure decrease in the fuel tank greater than an expected pressure decrease, where the expected pressure decrease is based on a fuel level in the fuel tank. 3. The method of claim 2, wherein the expected pressure decrease is further based on a temperature in the fuel tank, and wherein the delivering of fuel includes delivering fuel to all engine cylinders at a fuel flow rate above a non-zero upper threshold. 4. The method of claim 3, wherein the expected pressure decrease is further based on an ambient temperature. 5. The method of claim 2, wherein the expected pressure decrease is obtained from a lookup table based on a temperature in the fuel tank and fuel level in the fuel tank. 6. The method of claim 1, further comprising indicating a leak based on a rate of pressure decrease in the fuel tank greater than a threshold rate of pressure decrease. 7. The method of claim 6, wherein the threshold rate of pressure decrease is based on a fuel level in the fuel tank and a temperature in the fuel tank. 8. The method of claim 1, further comprising determining a size of the leak based on a rate of pressure decrease in the fuel tank. 9. The method of claim 1, further comprising determining a size of the leak based on a comparison of a pressure in the fuel tank with an expected pressure, where the expected pressure is based on a fuel level in the fuel tank and a temperature in the fuel tank. 10. The method of claim 1, further comprising, during an engine-off condition subsequent to the engine-on condition, indicating a leak based on a pressure in the fuel tank less than a threshold pressure. 11. The method of claim 1, further comprising indicating a leak based on a rate of pressure decrease in the fuel tank greater than a threshold rate of decrease following an engine-off event subsequent to the engine-on condition. 12. The method of claim 1, wherein the engine-on event is a key-on event. 13. A method for a vehicle with an engine and an evaporative emissions control system, comprising: while operating the engine, delivering fuel from a fuel tank to all engine cylinders at a fuel flow rate above a non-zero upper threshold while the fuel tank is sealed off from atmosphere; andindicating a leak in the evaporative emissions control system based on a pressure decrease in the fuel tank greater than an expected pressure decrease, where the expected pressure decrease is based on a fuel level in the fuel tank. 14. The method of claim 13, wherein the fuel level in the fuel tank is based on a fuel level reading of a fuel level sensor in the fuel tank, and where the fuel tank is sealed from an engine intake and any other gas conduit. 15. The method of claim 13, further comprising determining a size of the leak based on a comparison of the pressure decrease in the fuel tank with the expected pressure decrease. 16. The method of claim 13, wherein the vehicle is a plug-in hybrid electric vehicle. 17. A method for a vehicle with an engine, comprising: during an engine-on condition, delivering fuel from a fuel tank to one or more cylinders of the engine at a fuel flow rate above a non-zero upper threshold while the fuel tank is sealed off from atmosphere; andduring an engine-off condition subsequent to the engine-on condition, maintaining the fuel tank sealed off from the atmosphere and indicating a leak in response to a pressure decrease in the fuel tank greater than an expected pressure decrease, where the expected pressure decrease is based on a fuel level in the fuel tank. 18. The method of claim 17, wherein the expected pressure decrease is further based on a temperature in the fuel tank. 19. The method of claim 17, further comprising determining a size of the leak based on a comparison of the pressure decrease in the fuel tank with the expected pressure decrease.