Six other people were intoxicated after they approached the spill in Veracruz state to scoop up fuel, a police officer in the town of Ixtaczoquitlan said on condition of anonymity because he was not authorised to speak publicly.
The state civil protection agency said in a statement yesterday that a 43-year-old man died "from being close to the location and inhaling the vapours, fainting and falling in a gully."
Some 600 people were evacuated from heir homes while workers from the state-run Pemex energy firm worked to clean up the spill and fix the pipeline.
Illegal taps have caused environmental disasters and deaths in the past.
In April 2015, some 100,000 people were left without drinking water in the southern state of Tabasco after oil spilled into rivers.
In December 2010, an illegal tap caused a deadly explosion that killed 29 people in the central town of San Martin Texmelucan.