TLAHUELILPAN, Mexico — They were warned to stay away from the geyser of gasoline gushing from the illegally tapped pipeline in central Mexico, but Gerardo Perez says he and his son joined others in bypassing the soldiers. As they neared the spurting fuel, he was overcome with foreboding. Perez recalls telling his son: “Let’s go … this thing is going to explode.” And it did, with a fireball that engulfed locals scooping up the spilling gasoline and underscored the dangers of an epidemic of fuel theft from pipelines that Mexico’s new president has vowed to fight. By Saturday evening, the death toll from Friday’s blaze had risen to 73, with another 74 people injured and dozens more missing. Perez and his son escaped the flames.