Certain F-150, F-250, and Lincoln Blackwood pickups sold between 1997 and 2004 are affected.
The company says pickups purchased and driven only in warm-weather states like California should be OK.
In cold-weather states, road salt can cause metal straps holding up the tanks to rust. If the straps break, the tanks can hit the ground, rupture and catch fire.
To fix the latest problem, Ford will notify owners in September to bring their trucks to dealers. Mechanics will replace the straps with new ones coated to resist corrosion. Ford said that parts to fix the problem won't be widely available until then.
People with questions should contact their dealer, who can install a cable to hold the tanks in place until the replacement straps arrive, Sherwood said. They also can contact Ford at (866) 436-7332.
The trucks originally were sold or are now registered in Connecticut, Delaware, Illinois, Indiana, Iowa, Kentucky, Maine, Maryland, Massachusetts, Michigan, Minnesota, Missouri, New Hampshire, New Jersey, New York, Ohio, Pennsylvania, Rhode Island, Vermont, West Virginia, Wisconsin and Washington, D.C.
Ford's F-series pickup traditionally is the top-selling vehicle in the U.S.
The Associated Press contributed to this report.