The movie you are looking for is A CRY IN THE WILD (NOT to be confused with Cry of the Wild). I just copied this information off Amazon.com moments ago.
A CRY IN THE WILD (1990)
Our Price: $14.99
Starring: Jared Rushton, Ned Beatty, et al.
Director: Mark Griffiths
• NTSC format (US and Canada only)
• Color, Closed-captioned, HiFi Sound, NTSC
• ASIN: 6304365985
It is PG rated. There are some "words" (Kids love them.), one scene where Brian takes off his clothes to jump into the river (From a distance -- from the back -- kids love it!), a scene or two when the mom is hugging/kissing in flashbacks of "THE SECRET!" (Kids pretend to hate it!). I just sent a note home to parents explaining that movie is rated PG and gave them the opportunity to give or deny permission to watch. I teach 5th graders, and all 25 were readily granted permission. (Also I told parents that we were going to compare and contrast the book with the video. Of course we arrived at the conclusion that, as always, the book was much better than the movie!)
Have fun watching!