Patent ID: 7032576

Claim:
A method for controlling a fuel system and detecting faults within said fuel system, the fuel system including at least one fuel injector having at least one capillary flow passage, a heat source arranged along the at least one capillary flow passage, the heat source capable of heating the liquid fuel in the at least one capillary flow passage to a level sufficient to convert at least a portion thereof from the liquid state to a vapor state, the method comprising the steps of: (a) controlling power supplied to the heat source of the at least one fuel injector to achieve a predetermined target temperature, the predetermined target temperature operable to convert a portion of liquid fuel to the vapor state; (b) setting a resistance value for said heat source, the resistance value relatable to the predetermined target temperature; (c) determining if said resistance value is outside of a predetermined range; (d) if said resistance value is outside of a predetermined range, issuing a fault detection signal; and (e) adjusting said resistance value in response to physical changes to said capillary flow passage over time, said adjusting step comprising the sub-steps of: (i) measuring a value indicative of degree of engine warm-up; (ii) in the event that said value indicative of degree of engine warm-up is below a predetermined level then performing the following steps; (iii) measuring the cold resistance value for said capillary flow passage; (iv) measuring the intake ambient temperature; (v) determining if either said measured cold resistance value or said measured intake ambient temperature value matches previously stored measurement for each of said values respectively; and (vi) in the event neither said measured cold resistance value or said measured intake ambient temperature value matches the previously stored measurement for each of said values respectively, then adjusting a resistance value, said resistance value relatable to a predetermined target temperature for said capillary flow passage.