Method for controlling depressurisation in a motor vehicle fuel tank

A method (50) for controlling the depressurization of a container (10) of fuel of a motor vehicle, said motor vehicle comprising a fuel vapour exhaust system (20) connecting the tank (10) to a fuel vapour filter (23), the exhaust system (20) having an isolation valve (22) of the tank (10) and a rollover valve (21), the pressure inside the tank (10) being controlled by controlling the isolation valve (22), said method comprising the steps of:

• commanding (300) the initial opening (61) of the isolation valve in order to reduce the pressure inside the tank;
• determining (307) a blockage condition of the rollover valve based on at least information relating to the gradient of the pressure in the tank after the initial opening (61) of the isolation valve;
• and,
• if the blockage condition of the rollover valve is met, commanding (310) the closure (62) of the isolation valve, and controlling (300) re-opening (63) in order to further decrease the pressure in the tank,
• wherein determining the blockage condition of the rollover valve is determined on the basis of information (ΔP2/Δt2) relative to the gradient of the pressure in the tank which is evaluated based on values of the pressure in the tank measured after a first determined time (ΔT1) has elapsed after the initial opening (61) of the isolation valve, and wherein the method further comprises the following steps:
• determining (302) a blockage condition of the isolation valve as compared to a given threshold (Th) lower than the pressure (ΔP) in the tank for a specified period following the initial opening (61) of the isolation valve;
• and
• if the isolation valve blockage condition is met, generating (303) a piece of information (Stuck_FTIV) indicating that the isolation valve blockage condition is met, execution of the method steps of the depressurization of the fuel tank control being contingent on determining that said blockage condition of the isolation valve is not met.