Methods and systems are provided for conducting an ejector system diagnostic under conditions where an engine of a vehicle is not combusting air and fuel. In one example, a method comprises directing a positive pressure to the ejector system while the engine is off in order to communicate a negative pressure with respect to atmospheric pressure on a fuel system and an evaporative emissions system of the vehicle, and indicating that the ejector system is degraded responsive to the negative pressure not reaching a vacuum build threshold. In this way, the ejector system may be diagnosed under conditions where boosted engine operation is infrequent and/or of durations insufficient for conducting such an ejector system diagnostic.