SALT LAKE CITY—A tour bus that crashed and killed four Chinese tourists near a national park in Utah in 2019 had problems earlier that day with the engine not starting, according to a new documents released Wednesday by U.S. authorities investigating the incident. The driver of the bus had to do a video call from a gas station with his boss, who told him to crawl under the bus and give the starter “two good hits.” That worked, and the bus started, according to new documents released by the National Transportation Safety Board (NTSB) detailing the investigation. Soon after, the driver lost control of the bus and veered off the road when he tried to correct course on Sept. 20, 2019, near Bryce Canyon National Park. The bus rolled, hitting a guard rail, crushing the roof and throwing people from the vehicle. All 30 passengers were hurt, with 17 suffering …