1 fire (something) up or fire up (something)
a : to start (something) by lighting a fire
We fired up the grill for the barbecue.
b : to cause (something) to start working
I fired up my computer and got down to work.
Before we start working let's fire up the coffeemaker.
2 fire (someone) up or fire up (someone) : to fill (someone) with energy or enthusiasm
The coach fired up the players with a pep talk.
— usually used as (be/get) fired up
We were fired up for the concert.