System and methods for preventing hydrocarbon breakthrough emissions

A method comprising:

• propelling a motor vehicle by either a combustion engine or an electric motor;
• supplying fuel to said combustion engine from a fuel tank which in turn is coupled to an adsorbent that adsorbs fuel vapors generated in said tank;
• and
• in response to detecting breakthrough of said vapors from said adsorbent while said combustion engine is not combusting:
• turning said combustion engine with said electric motor until an intake valve and an exhaust valve of a cylinder of said combustion engine are simultaneously open;
• and forcing air through said adsorbent, into said engine, and then into a catalyst coupled to said exhaust valve, to route vapors from said adsorbent through said engine and then into said catalyst.

A system for a vehicle comprising:

• a combustion engine comprising one or more cylinders, each cylinder comprising an intake valve and an exhaust valve;
• an exhaust catalyst coupled to a combustion engine exhaust;
• a fuel vapor canister comprising an adsorbent for adsorbing fuel vapors coupled to an engine intake via a canister purge valve and to atmosphere via a canister vent valve;
• a fuel tank coupled to said fuel vapor canister via a fuel tank isolation valve;
• a throttle coupled between said engine intake and atmosphere;
• an air pump coupled between said fuel vapor canister and said atmosphere;
• a hydrocarbon sensor coupled between said fuel vapor canister and said atmosphere;
• and
• a controller configured with instructions stored in non-transitory memory, that when executed cause the controller to:
• in response to detecting breakthrough of adsorbed fuel vapors from said fuel vapor canister while said engine is off:
• heat said exhaust catalyst;
• position a first engine cylinder with an intake valve open and an exhaust valve open;
• close said throttle;
• open said canister purge valve;
• close said fuel tank isolation valve;
• turn said air pump on;
• and
• operate said air pump to force air through said adsorbent, into said cylinder, and then into said exhaust catalyst, to route vapors from said adsorbent through said cylinder and then into said exhaust catalyst.