Diagnostic Aids
WARNING: This page is about a different car, the 2001 GMC Savana, 2001 Chevrolet RV Cutaway, 2001 Chevrolet Cutaway, and 2001 Chevrolet Chevy Express. However, it is still accessible from the selected car via links, so may be relevant.
An intermittent condition could be caused by a damaged EVAP vent housing, a temporary blockage at EVAP vent valve inlet or a pinched vent hose. A blockage in vent system will also cause a poor fuel fill problem.