fuel vs keep burning

fuel

noun
  • Substance that provides nourishment for a living organism; food. 

  • Substance consumed to provide energy through combustion, or through chemical or nuclear reaction. 

  • Something that stimulates, encourages or maintains an action. 

verb
  • To exacerbate, to cause to grow or become greater. 

  • To provide with fuel. 

keep burning

How often have the words fuel and keep burning occurred in a corpus of books? (source: Google Ngram Viewer )