Patent ID: 7710250

Claim:
A system for verifying fuel cap engagement, comprising: a transducer, coupled to a purge line of a fuel vapor recovery system to generate an electrical measurement signal corresponding to one of vapor pressure and vapor flow rate in the purge line; a monitor to: receive the electrical measurement signal; estimate, for a measured vapor flow rate, a corresponding vapor pressure in the purge line, the estimated vapor pressure value being equivalent to a measured vapor pressure value; estimate for a measured vapor pressure, a corresponding vapor flow rate in the purge line, the estimated vapor flow rate value being equivalent to a measured vapor flow rate value; correlate the electrical measurement signal and the estimated value to generate a dataset comprising data points relating vapor pressure to a corresponding vapor flow rate at predetermined time intervals; utilize the dataset to compute a linear approximation of pressure versus flow rate; and utilize the dataset to compute a curve approximation of pressure versus flow rate; and an indicator coupled to the monitor, wherein the monitor actuates the indicator when the difference between the computed linear and curve approximations is less than a predetermined threshold value.