Leak Check Sequence

Leak Check Sequence

A = Pump motor current; B = Time X = Current draw for tight system; Y = Current draw for minor leak; Z = Current draw for major leak

1 Pump motor energised: Air directed through reference orifice to atmosphere, to establish reference current. 2 Reference current. 3 Change-over valve energised: Air directed through EVAP canister into fuel tank. 4 Major leak check completed: If current is above stored value, no major leak present; if current is below stored value, major leak present. 5 Minor leak check completed, with no minor leak detected, when current exceeds reference value. 6 Minor leak check completed, with minor leak detected, when current stabilises at or below reference current.