to havealmostreachedapointwhere you areunabletocontinue, because you havealmostnoenergy,money, etc.left:
Thehurricanedestroyedhishomeandlefthim and hisfamilyrunningonfumes.
She isdeterminedtoplayin today'sgame,evenif she isrunningonfumesby the end of it.
Heplaysastrugglingwriterwhoseself-confidenceisrunningonfumes.