Running out of gas, itself, is not a violation of the vehicle code (yet). However, be aware that:
§ 22456. Ice cream vending truck safety
(a) This section shall be known and may be cited as the Destiny Nicole Stout Memorial Act.
(b) The Legislature finds and declares that motor vehicles engaged in vending ice cream and similar food items in residential neighborhoods can increase the danger to children, and it is necessary that these vehicles are clearly seen and noticed by motorists and pedestrians to protect public safety.
(c) As used in this section, the term "ice cream truck" means a motor vehicle engaged in the curbside vending or sale of frozen or refrigerated desserts, confections, or novelties commonly known as ice cream, or prepackaged candies, prepackaged snack foods, or soft drinks, primarily intended for the sale to children under 12 years of age.
(d) Any ice cream truck shall be equipped at all times, while engaged in vending in a residential area, with signs mounted on both the front and the rear and clearly legible from a distance of 100 feet under daylight conditions, incorporating the words "WARNING" and "CHILDREN CROSSING." Each sign shall be at least 12 inches high by 48 inches wide, with letters of a dark color and at least four inches in height, a one-inch wide solid border, and a sharply contrasting background.
(e) A person may not vend from an ice cream truck that is stopped, parked, or standing on any public street, alley, or highway under any of the following conditions:
(1) On a street, alley, or highway with a posted speed limit greater than 25 miles per hour.
(2) If the street, alley, or highway is within 100 feet of an intersection with an opposing highway that has a posted speed limit greater than 25 miles per hour.
(3) If the vendor does not have an unobstructed view for 200 feet in both directions along the highway and of any traffic on the highway.
