What are you, a glutton for punishment? It's not stated that the zombies care if they are on fire. It's not a given that they'll scatter, or even notice. What if they don't notice? You still have zombies after you, only now they are flaming zombies.
You know who might be the first to survive a zombie outbreak? Your friendly neighborhood mathematician. The BBC reports on research from the University of Ottawa and Carleton University that illustrates how quickly humans would succumb to a zombie outbreak. As professor Robert Smith?* tells the BBC, "We model a zombie attack using biological assumptions based on popular zombie movies. We introduce a basic model for zombie infection and illustrate the outcome with numerical solutions." (* BBC notes that the question mark is part of the professor's name.)
It would be extremely important for humans to "hit hard and fast," otherwise humanity would be doomed, according to the researchers.