| 摘要 |
PURPOSE:To prohibit the erroneous judgment in the case when percolation is generated in a carburetor by prohibiting the judgment of trouble of an air-fuel ratio controller in the continuous operation of an engine body after the temperature of the engine body becomes over a set value. CONSTITUTION:As for an engine body 1, a variable vneturi type carburetor 3 is installed in an intake passage 2, and an oxygen concentration sensor 13 is installed in an exhaust passage 14. An air bleed valve control valve 11 installed in a fuel passage 7 is operated on the basis of the detection signal of the detector 13, and the air-fuel ratio is feedback-controlled. In this case, after the temperature of the engine body 1 which is detected by a means A becomes over a set value, a means B judges if the engine body 1 is in the continuous operation or not. When the engine body 1 is in the continuous operation, the trouble judgement by a means D for judging the trouble of an air-fuel ratio controller on the basis of the feedback control signal is prohibited by a means C.
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