Patent ID: 9353708
Filing Date: 2016-05-31
CPC Classification: F02D,F02M,G01M,Y10T

Claim Text:
1. A method of monitoring a fuel vapor recovery system, comprising, modulating a fuel tank isolation valve (FTIV) coupled between a fuel tank and a canister of the fuel vapor recovery system; and indicating FTIV degradation based on pressure pulsations upstream and/or downstream of the FTIV responsive to the modulation, wherein the modulation is performed during an engine-off condition in response to obtaining a threshold pressure difference across the FTIV, and wherein the modulation includes intermittently opening the FTIV with a duty cycle based on a bandwidth of the valve, wherein an increased modulation duty cycle is applied during higher pressure differential conditions relative to the threshold pressure difference, and a decreased modulation duty cycle is applied during lower pressure differential conditions relative to the threshold pressure difference.