A: Are you all right? You look a bit under the weather today.

B: After two nights of continuous work, I’m running on fumes.

Note: This idiom means “continuing to operate with no or very little enthusiasm, energy, or resources left.” This phrase is in reference to an automobile which is low on fuel, but is still running. For example: Having traveled for the better part of the previous two days, the team was running on fumes on the day of the match and lost.