Automotive evaporative emission leak detection system and method

A leak detection test method for an evaporative emission space of a fuel storage system of an automotive vehicle comprising:

• creating a differential between pressure in an evaporative emission space and atmospheric pressure and regulating, by a regulator valve, the created differential to a defined differential sufficient to perform a leak detection test on the evaporative emission space;
• isolating the evaporative emission space so that reduction in the regulated created differential is indicative of leakage from the evaporative emission space;
• and
• sensing reduction in the regulated created differential;
• in which the step of sensing reduction in the regulated created differential comprises sensing such reduction by a sensor that develops an electric signal indicative of such reduction;
• and
• including the step of detecting a substantially constant rate of reduction in the regulated created differential by detecting substantially constant rate of change in the electric signal, and then measuring the rate of change in the electric signal over a defined time interval.

A leak detection test method for an evaporative emission space of a fuel storage system of an automotive vehicle comprising:

• creating a differential between pressure in an evaporative emission space and atmospheric pressure and regulating, by a regulator valve, the created differential to a defined differential sufficient to perform a leak detection test on the evaporative emission space;
• isolating the evaporative emission space so that reduction in the regulated created differential is indicative of leakage from the evaporative emission space;
• and
• sensing reduction in the regulated created differential;
• including the step of detecting a substantially constant rate of reduction in the regulated created differential, and then measuring the reduction over a defined time interval.