Systems and methods for fuel filter diagnostics

Patent metadata

Field	Value
Publication number	US-10968852-B2
Application number	US-201815921605-A
Country	US
Kind code	B2
Filing date	Mar 14, 2018
Priority date	Mar 14, 2018
Publication date	Apr 6, 2021
Grant date	Apr 6, 2021

Abstract

Methods and systems are provided for controlling a fuel system of a vehicle to diagnose whether a fuel filter is functioning as desired. In one example, a method may include, in response to a fuel rail pressure decreasing below a threshold pressure while an engine of the vehicle is running, diagnosing whether degradation of fuel injectors or a fuel pressure regulator of the vehicle has occurred while the engine is not running. Then, only if degradation of the fuel injectors and fuel pressure regulator has not occurred, a fuel filter cleaning routine is performed.

First claim

The invention claimed is:

1. A method, comprising:
responsive to an engine fuel rail pressure decreasing below a threshold pressure, determining degradation of any of a plurality of engine fuel system components including a fuel injector, a fuel regulator, and a fuel line coupled to a fuel pump;
if the determining of degradation determines degradation of any of the plurality of engine fuel system components has occurred, indicating the degradation without performing a fuel filter cleaning routine;
if the determining of degradation does not determine degradation of any of the plurality of engine fuel system components has occurred, then adjusting operation of the fuel pump to perform the fuel filter cleaning routine, and following performance of the fuel filter cleaning routine, responsive to the engine fuel rail pressure remaining below the threshold pressure, indicating fuel system degradation.

2. The method of claim 1 , wherein adjusting operation of the fuel pump to perform the fuel filter cleaning routine includes performing a plurality of fuel pulse cycles throughout a cycling duration, with the fuel pump and the fuel filter being disposed within a fuel tank.

3. The method of claim 2 , wherein each fuel pulse cycle of the plurality of fuel pulse cycles includes pulsing fuel through the fuel pump and the fuel filter in a forward direction and, after pulsing fuel through the vehicle fuel pump and the fuel filter in the forward direction, pulsing fuel through the fuel pump and the fuel filter in a reverse direction opposite to the forward direction and away from a fuel rail.

4. The method of claim 3 , wherein pulsing the fuel through the fuel pump and the fuel filter in the reverse direction includes providing a negative electrical voltage to the fuel pump.

5. The method of claim 1 , wherein determining whether degradation of any of the plurality of engine fuel system components has occurred includes:
operating the fuel pump in a forward direction for a flow duration to flow fuel to the engine fuel rail; and
while operating the fuel pump in the forward direction for the flow duration:
diagnosing degradation of the fuel injector by adjusting operation of the fuel injector and determining an air/fuel ratio in an exhaust passage of the engine; and
diagnosing degradation of the fuel regulator or the fuel line by determining a vapor pressure in a fuel tank while sealing the fuel tank from atmosphere, the fuel regulator and the fuel pump and the fuel line each positioned within the fuel tank.

6. The method of claim 5 , wherein operating the fuel pump in the forward direction includes providing a positive electrical voltage to the fuel pump.

7. The method of claim 5 , wherein adjusting operation of the fuel injector includes fully closing a nozzle of the fuel injector throughout the duration and not opening the nozzle throughout the duration.

8. The method of claim 5 , wherein determining the vapor pressure in the fuel tank includes measuring the vapor pressure via a vapor pressure sensor coupled to the fuel tank.

9. The method of claim 5 , wherein sealing the fuel tank from atmosphere includes moving a fuel tank isolation valve to a fully closed position.

10. The method of claim 5 , wherein determining the air/fuel ratio includes measuring the air/fuel ratio via one or more sensors coupled to the exhaust passage.

11. The method of claim 10 , wherein measuring the air/fuel ratio via the one or more sensors includes measuring an amount of oxygen in the exhaust passage via a heated exhaust gas oxygen sensor.

12. A method, comprising:
operating an engine of a vehicle for a first duration and comparing a pressure of fuel in an engine fuel rail to a threshold pressure throughout the first duration; and
responsive to both of the pressure of fuel in the engine fuel rail decreasing below the threshold pressure at least once during the first duration and an engine key-off request:
running the engine unfueled for a second duration while monitoring an air/fuel ratio in an exhaust passage coupled to the engine throughout the second duration;
sealing an engine evaporative emissions system coupled to a fuel tank of the vehicle and monitoring a fuel vapor pressure within the fuel tank for a third duration; and
adjusting operation of a fuel pump coupled between the fuel tank and the fuel rail responsive to both of the air/fuel ratio and the fuel vapor pressure, wherein
in response to the air/fuel ratio being less than a threshold air/fuel ratio or the fuel vapor pressure being greater than a threshold fuel vapor pressure, stopping a flow of fuel through the fuel pump; and
in response to the air/fuel ratio being greater than a threshold air/fuel ratio for the second duration and the fuel vapor pressure being less than a threshold fuel vapor pressure for the third duration, pumping fuel in a reverse direction of the fuel pump through a fuel filter.

13. The method of claim 12 , wherein pumping fuel in the reverse direction of the fuel pump includes flowing fuel from an outlet of the fuel pump to an inlet of the fuel pump, the outlet fluidly coupling the fuel pump to the engine fuel rail via a fuel line, the inlet fluidly coupling the fuel pump to the fuel filter and fuel stored within the fuel tank.

14. The method of claim 12 , wherein pumping the fuel in the reverse direction of the fuel pump through the fuel filter occurs during each pulse of a plurality of pulses of fuel through the fuel pump and the fuel filter.

15. The method of claim 14 , wherein each pulse of the plurality of pulses further includes pumping fuel in a forward direction of the fuel pump opposite to the reverse direction, before pumping fuel in the reverse direction.

16. A system, comprising:
an engine;
a fuel rail including a plurality of fuel injectors coupled to cylinders of the engine;
a fuel tank having a fuel pump and a fuel filter disposed therein, the fuel pump fluidly coupled to the fuel rail;
a plurality of fuel tank pressurized components consisting of a fuel pressure regulator and one or more fuel lines disposed within the fuel tank; and
an electronic controller including first computer readable instructions stored on non-transitory memory that when executed cause the controller to:
determine whether a fuel rail pressure is less than a threshold fuel rail pressure before an engine key-off request and while the engine is running and combusting fuel/air; and
after the engine key-off request and before an engine key-on request with no other engine key-on requests therebetween, in response to the fuel rail pressure being less than the threshold fuel rail pressure:
determine whether degradation of one or more fuel injectors of the plurality of fuel injectors has occurred;
determine whether degradation of any of the plurality of fuel tank pressurized components has occurred;
in response to determining that degradation of the one or more fuel injectors or any of the plurality of fuel tank pressurized components has occurred, indicating degradation of a fuel system component without performing a fuel filter cleaning routine; and
in response to determining that degradation of the one or more fuel injectors has not occurred and degradation of any of the plurality of fuel tank pressurized components has not occurred, performing the fuel filter cleaning routine.

17. The system of claim 16 , further comprising an electrical circuit coupling the fuel pump to a power source, the electrical circuit including a first set of switches coupled to a first voltage input and a second set of switches coupled to a

Assignees

• Ford Global Tech Llc

Inventors

• Dudar Aed
• Leone Thomas
• Miller Kenneth

Classifications

• F02M37/0076 Primary

  Details of the fuel feeding system related to the fuel tank (vehicle fuel tanks B60K15/03) · CPC title

• F02M65/007

  Cleaning · CPC title

• F02D41/22 Primary

  Safety or indicating devices for abnormal conditions {(in air/fuel ratio feedback systems F02D41/1495, in electric control linkage F02D11/107, in purge control systems F02M25/0809)} · CPC title

• F02D41/003

  Adding fuel vapours, e.g. drawn from engine fuel reservoir · CPC title

• B01D35/005

  Filters specially adapted for use in internal-combustion engine lubrication or fuel systems · CPC title