TECHNOLOGY FOCUS - COMPUTING AND CONTROL - Preferred Method: The determining step includes sensing the amount of soot within the fuel reformer by generating a soot-accumulation-control signal when the amount of soot within the reformer reaches a predetermined accumulation level, and the step of advancing second air/fuel mixture is performed in response to generation of the soot-accumulation-control signal. Advancing the second air/fuel mixture is performed for a predetermined time to purge the fuel reformer of soot. The determining step may include determining if a predetermined time has elapsed since the fuel reformer was last purged of soot and generating a time-lapsed-control signal in response to the determination, and the step of advancing second air/fuel mixture is performed in response to generation of the time-lapsed control signal. In other embodiment, the determining step includes detecting a reformer shutdown-request control signal or generating a high-load control signal when an engine associated with the fuel reformer experiences a high load condition, and the step of advancing the second air/fuel mixture is performed in response to detection of reformer shutdown request control signal or generation of high-load control signal. A third air/fuel mixture having the first air-to-fuel ratio may be advanced into the fuel reformer subsequent to the step of advancing the second air/fuel mixture. The second air/fuel mixture is devoid of fuel. Alternatively, operating a fuel reformer includes advancing air in the absence of fuel into a housing of fuel reformer to combust soot present, advancing a mixture of fuel and air into the fuel reformer housing prior to advancing air in the absence of fuel, and advancing air in the presence of fuel into the fuel reformer housing subsequent to completion of advancing air in the absence of fuel. The method may include determining the amount of soot within the fuel reformer housing and determining if a predetermined time has elapsed since soot was last purged from the fuel reformer, and the advancing step includes advancing air in the absence of fuel if the amount of soot within the fuel reformer housing is greater than or equal to a predetermined amount and when the predetermined time has lapsed.    TECHNOLOGY FOCUS - MECHANICAL ENGINEERING - Preferred Components: The air/fuel input assembly comprises a fuel injector and/or an electrically operated air inlet valve (40), and the reformer controller is electrically coupled to the fuel injector and/or air inlet valve. A sensor (34) senses the amount of soot within the fuel reformer. The fuel reformer assembly is a plasma fuel reformer.