This is from The Flash #167. It's written by Gardner Fox and illustrated by Carmine Infantino.
The story begins with Flash going after some jewel smugglers when suddenly his uniform catches on fire; he's lost the protective body aura that safeguards him from the friction caused by super-speed. Flash jumps into the water to douse the flames.
Flash considers giving up his powers, but thinks about all the good he's done with them.
After his ad is placed in the newspaper, Flash goes across the country with Mopee, delivering various packages.