Fault diagnosis method for fuel evaporation system

The invention relates to the technical field of automobile fault diagnosis methods, in particular to a fault diagnosis method for a fuel evaporation system. A first pressure sensor, a second pressure sensor and a plurality of electromagnetic valves are additionally arranged on the fuel evaporation system; the method comprises the following steps that S1, an electromagnetic valve is adjusted, the pressure value P11 of a first pressure sensor is collected, whether the fault of clamping stagnation of a flushing valve or leakage of a connecting pipe occurs or not is judged, if not, the pressure value P12 of a second pressure sensor is collected, whether the fault of carbon tank blockage occurs or not is judged, and if not, the next step is executed; s2, an electromagnetic valve is adjusted, the pressure value P21 of a first pressure sensor is collected, whether the fault of breather pipe leakage or circulating pipe leakage occurs or not is judged, and if not, the next step is executed; and S3, the electromagnetic