Abstract: A system and method for adjusting fuel vapor delivery from a fuel vapor recovery system in an internal combustion engine. An engine controller calculates a purge fuel fraction that is indicative of an amount of fuel vapor passing through the vapor recovery system relative to a total amount of purge flow, including air, passing through the vapor recovery system. A purge percent fuel parameter indicative of an amount of fuel vapor delivered to the engine from the fuel vapor recovery system relative to a total amount of fuel delivered to the engine is calculated based on the purge fuel fraction. Finally, the controller adjusts an amount of fuel vapor released from the vapor recovery system based on the purge percent fuel parameter.

Abstract: A system and method for adjusting fuel vapor delivery from a fuel vapor recovery system in an internal combustion engine. A requested amount of fuel vapor delivery is determined based upon a desired fuel vapor delivery amount and various system constraints, which ensure continued optimal operation of the vehicle. Purge fuel ratios are calculated by comparing desired levels to actual levels of various operating parameters. The purge fuel ratios are compared to each other to determine the minimum value from among the various purge fuel ratios, which is indicative of the most limiting system constraint. The most limiting system constraint is used to calculate an amount of fuel vapor to be delivered from the vapor recovery system.