Firing up means starting or powering on a device or process, like an engine, grill, or app. It also means rousing strong feelings in people, such as excitement, drive, or anger.
It's an illusion I've noticed before-- words on a page are like oxygen to a petrol engine, firing up ghosts. It only lasts while the words are in your head. After you put down the paper or pen, the pistons fall lifeless again. Elizabeth Wein