Leak detection system and method having self-compensation for changes in pressurizing pump efficiency

摘要

A leak detection system for a fuel system of an automotive vehicle has a diaphragm pump that is repeatedly stroked to pressurize vapor containment space of the fuel system during a leak detection test. A restriction is disposed between the pump and the space being pressurized to cause a real time pressure trace of pressure between the pump and the restriction to comprise a succession of pulses having peaks and valleys. Data from the first pump burst of the trace is used to adjust the number of times the pump is stroked during subsequent bursts to maintain substantially constant mass airflow into the space during each burst, thereby compensating for change in pump efficiency.