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A system for verifying fuel cap engagement utilizes a transducer coupled to a purge line of a fuel vapor recovery system to generate an electrical signal corresponding to one of the vapor pressure and the vapor flow rate in the purge line. A monitor receives the electrical signal and estimates the v

A system for verifying fuel cap engagement utilizes a transducer coupled to a purge line of a fuel vapor recovery system to generate an electrical signal corresponding to one of the vapor pressure and the vapor flow rate in the purge line. A monitor receives the electrical signal and estimates the vapor pressure when the electrical signal corresponds to the vapor flow rate. The monitor likewise estimates the vapor flow rate when the electrical signal corresponds to the vapor pressure. The monitor also correlates the electrical signal and the estimate to generate a dataset relating vapor pressures to corresponding vapor flow rates at predetermined time intervals, computes a linear approximation of pressure versus flow rate, and computes a curve approximation of pressure versus flow rate. An indicator is actuated by the monitor when the difference between the computed linear and curve approximations is less than a predetermined threshold value.

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What is claimed is: 1. 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 e

What is claimed is: 1. 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. 2. The system of claim 1 wherein the electrical measurement signal corresponds to the vapor pressure in the purge line and the monitor estimates a vapor flow rate in the purge line corresponding to the vapor pressure. 3. The system of claim 1 wherein the electrical measurement signal corresponds to the vapor flow rate in the purge line and the monitor estimates a vapor pressure in the purge line corresponding to the vapor flow rate. 4. The system of claim 1 wherein the transducer generates at least one of an analog and digital electrical signal having at least one of variable resistance, capacitance, inductance, voltage, current and digital data corresponding to one of the vapor pressure and the vapor flow rate. 5. The system of claim 1 wherein the monitor comprises at least one of analog and digital electronic circuitry. 6. The system of claim 5 wherein the monitor further comprises at least one of a memory storage device and a predetermined set of instructions. 7. The system of claim 1 where in the indicator is at least one of a warning light, visual display, speaker, piezoelectric sounder and chime. 8. The system of claim 7 wherein the indicator is a standalone device. 9. The system of claim 7 wherein the indicator is a constituent element of a multi-function vehicle system. 10. The system of claim 1 wherein the monitor computes a linear approximation of vapor pressure versus vapor flow rate using linear regression to derive a straight-line equation. 11. The system of claim 1 wherein the monitor computes a curve approximation of vapor pressure versus vapor flow rate using curve fitting regression to derive an equation having at least one of polynomial, exponential and logarithmic terms. 12. The system of claim 1 wherein the threshold value for actuating the indicator is established at one of a predetermined vapor flow rate, a predetermined vapor pressure, a plurality of predetermined vapor flow rates, a plurality of vapor pressures, a predetermined range of vapor flow rates and a predetermined range of vapor pressures. 13. A system for verifying fuel cap engagement, comprising: a first transducer, coupled to a purge line of a fuel vapor recovery system to generate a first electrical signal corresponding to the vapor pressure in the purge line; a second transducer, coupled to the purge line to generate a second electrical signal corresponding to the vapor flow rate in the purge line; a monitor to: receive the first and second electrical signals; correlate the first and second electrical signals 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 linear and curve approximations is less than a predetermined threshold value. 14. A method for verifying fuel cap engagement, comprising the steps of: measuring one of the pressure and the flow rate of fuel vapor in a purge line of a fuel vapor recovery system; estimating the flow rate of fuel vapor in the purge line when the vapor pressure is measured, the estimated flow rate value being equivalent to a measured flow rate value; estimating the pressure of fuel vapor in the purge line when the vapor flow rate is measured, the estimated pressure value being equivalent to a measured pressure value; correlating the pressure and flow rate measurements and estimated values at predetermined time intervals; computing a linear approximation of pressure versus flow rate in the purge line; computing a curve approximation of pressure versus flow rate in the purge line; computing the difference between the linear and curve approximations; and actuating an indicator if the computed difference is less than a predetermined threshold value. 15. The method of claim 14, fun her comprising the step of selecting a transducer to measure at least one of the fuel vapor pressure and the fuel vapor flow rate, the transducer generating at least one of an analog and digital electrical signal having at least one of variable resistance, capacitance, inductance, voltage, current and digital data corresponding to one of the vapor pressure and the vapor flow rate. 16. The method of claim 14, fun her comprising the step of selecting at least one of a warning light, visual display, speaker, piezoelectric sounder and chime for the indicator. 17. The method of claim 16, further comprising the step of configuring the indicator as a standalone device. 18. The method of claim 16, further comprising the step of configuring the indicator as a constituent element of a multi-function vehicle system. 19. The method of claim 14, further comprising the step of computing a linear approximation of vapor pressure versus vapor flow rate using linear regression to derive a straight-line equation. 20. The method of claim 14, further comprising the step of computing a curve approximation of vapor pressure versus vapor flow rate using curve fitting regression to derive a curve equation having at least one of polynomial, exponential and logarithmic terms. 21. The method of claim 14, further comprising the step of setting the threshold value for actuating the indicator at one of a predetermined vapor flow rate, a predetermined vapor pressure, a plurality of predetermined vapor flow rates, a plurality of vapor pressures, a predetermined range of vapor flow rates and a predetermined range of vapor pressures. 22. A method for verifying fuel cap engagement, comprising the steps of: measuring the pressure of fuel vapor in a purge line of a fuel vapor recovery system; measuring the flow rate of fuel vapor in the purge line; correlating the pressure and flow rate measurements at predetermined time intervals; computing a linear approximation of pressure versus flow rate in the purge line; computing a curve approximation of pressure versus flow rate in the purge line; computing the difference between the linear and curve approximations; and actuating an indicator if the computed difference is less than a predetermined threshold value.