A stoppage in a pipeline caused by gas bubbles (especially a stoppage that develops in hot weather in an internal-combustion engine when fuel in the gas line boils and forms bubbles that block the flow of gasoline to the carburetor) WordNet 3.0 & Open English WordNet

Vapor lock is a problem caused by liquid fuel changing state to gas while still in the fuel delivery system of gasoline-fueled internal combustion engines. Wikipedia

Liquid fuel prematurely gasifying Wikidata

A problem mostly affecting gasoline-fueled internal combustion engines, where the liquid fuel changes state from liquid to gas while still in the fuel delivery system, reducing the pump pressure and causing transient power loss or complete stalling. Wiktionary