Systems and methods for detection and mitigation of liquid fuel carryover in an evaporative emissions system

A method for a fuel system, comprising:

• following a refueling event, monitoring a fuel tank pressure bleed-down rate;
• indicating a presence of liquid fuel in an evap recovery line responsive to a first fuel tank pressure bleed-down rate less than a threshold;
• actively returning the liquid fuel in the evap recovery line to a fuel tank;
• and
• responsive to the first fuel tank pressure bleed-down rate being greater than the threshold, sealing the fuel tank responsive to a fuel tank pressure decreasing to atmospheric pressure, and updating a canister purge schedule.

A fuel system, comprising:

• a fuel tank coupled to a fuel vapor canister via one or more evap recovery lines;
• a fuel tank isolation valve coupled between the fuel tank and the fuel vapor canister;
• a fuel tank pressure sensor;
• a fuel tank fill level sensor;
• an evaporative leak check module comprising a reversible vacuum pump coupled between the fuel vapor canister and atmosphere;
• and
• a controller storing instructions in non-transitory memory that, when executed, cause the controller to:
• receive a request for a refueling event;
• open the fuel tank isolation valve;
• monitor a fuel tank pressure via the fuel tank pressure sensor and a fuel tank fill level via the fuel tank fill level sensor for a duration of the refueling event;
• indicate liquid fuel carryover into the one or more evap recovery lines responsive to a first fuel tank pressure decay rate following the refueling event being less than a threshold;
• and
• responsive to an indication of liquid fuel carryover into the one or more evap recovery lines, activate the reversible vacuum pump to direct atmospheric air into the fuel system.