Patent ID: 6886398

Claim:
A fuel vapor pressure monitoring device monitoring a pressure increase in a purge vent between a fuel tank and an intake passage of an engine, in a sealed state, the device comprising: a sensor which detects a pressure in the purge vent; and a programmable controller programmed to: repeatedly calculate a pressure change rate in the purge vent in the sealed state at predetermined time intervals; update a minimum value for the pressure change rate, calculate a difference of the minimum value and the pressure change rate, calculate an error equivalence amount based on a time integral of the difference, the error equivalence amount corresponding to an error amount in the pressure in the purge vent in the sealed state due to sloshing in the fuel tank; and calculate a corrected pressure which corresponds to a pressure when sloshing does not occur, from the pressure in the purge vent in the sealed state and the error equivalence amount.