Idiom: To be running on fumes – to continue to do something or stay awake when there is almost no energy left to do it.
Context #1 – Two friends talking
Vincent: Hey, Brandy! Oh my God, you look so tired. Are you OK?
Brandy: Not really. I still haven't finished this paper I have to write for my English class. I stayed up all night trying to finish it.
Vincent: Oh no! Are you almost done?.
Brandy: Yes, maybe I can finish it if I can stay awake and focus. At this point, I'm just running on fumes and I don't know how much longer I can do this.
Vincent: Why don't you have a large cup of coffee? I can help you finish it right now. I have time.
Brandy: Really? Thank you so much!
Context #2 – Talking about a soccer match
Selena: That was such a great match! Both teams were playing so hard and wanted to win.
Patricio: I know. You could tell that the other team, the Sharks, were just running on fumes at the end. They just didn't have the strength of the home team.
Selena: Yeah, I guess so. They did look really tired.
Patricio: Well, I'm glad our team was able to keep going and finally win.
Meaning: To be running on fumes means to continue to do something or stay awake when there is almost no energy left to do it. This is said about a person or people, but it specifically refers to the last fumes of gasoline in an empty tank in a car. In context 1, Brandy has been up all night writing a paper and is super tired. However, she still has to finish the paper. She is running on fumes at this point. In context 2, Selena and Patricio have just been watching a soccer match and one of the teams looks really tired. That team was just running on fumes and eventually lost.