What does "tank up" mean?

Fill a gas tank with fuel, as in As soon as we tank up the car we can leave. [First half of 1900s]

Drink to the point of intoxication. F. Scott Fitzgerald used this expression in The Great Gatsby (1926): “I think he'd tanked up a good deal at luncheon.” This expression often is put in the passive, meaning “be or become intoxicated,” as in My roommate really got tanked up last night. [Slang; c. 1900]