P.K. and the Kid (1987)

P.K. runs away from home because her stepfather keeps harassing her sexually and her mother ignores this problem. She hides in the loading space of Kid Kane's pickup, who's on the way to the world championships in arm-pressing. When he discovers her, he wants to send her home at first, but after he knows the story he takes her with him--and gets himself into big trouble: her furious stepfather is on their trail, trying to kidnap her and avenge the stress he got from her mother.