WASHINGTON — Federal regulators closed two investigations into safety issues in Ford Motor Co. vehicles —deciding that a recall of 1.1 million F-150s and other trucks was sufficient to address concerns, the government said Thursday.

The National Highway Traffic Safety Administration said it was closing its investigation into more than 1 million F-150 trucks after it was satisfied with Ford's recall, reported The Detroit News.

In August, Ford said it was calling back 1997-2004 F-150s in "salt-belt" states after reviewing 700 complaints of corrosion of steel straps holding up fuel tanks.

Most of reports involved one or both straps failing — and about half involved the tank dropping and or dragging on the ground. There were 180 reports of leaking fuel.

Ford said 97 percent of complaints came from states that use large amounts of road salt.

Ford received two reports of a vehicle fire destroying a vehicle and a third in which a fire destroyed the vehicle and injured a driver.

"Ford's recall action appears to adequately address the problem at this time," NHTSA said in a report closing its investigation.

The recall covers some 1997-1999 F-250 and 2002-2003 Lincoln Blackwood trucks. The recall covers vehicles sold or registered in 21 salt-belt states, including Michigan, Ohio, New York, Pennsylvania and Indiana, and the District of Columbia.

Separately, NHTSA said it is also closing an investigation into 387,354 2010-2011 Ford Escape and Mercury Mariner SUVs into complaints that the liftgate glass shattered without warning.

NHTSA said it reviewed nearly 300 complaints into the issue, including 15 minor injuries.

Ford acknowledged a higher than normal level of glass breakage incidents in the 2010 model year and early 2011 vehicles.

Ford investigated the incidents "but failed to identify an anomaly in the glass manufacturing process" to explain the spike in reports, NHTSA said.

In November, Ford issued a Technical Service Bulletin to include broken liftgate glass on all 2010 Escape and Mariners — as well as some 2011 models.

In September 2004, Ford recalled about 955,000 Ford Explorer and Mercury Mountaineer SUVs from the 2002 and 2003 model years to replace the liftgate glass strut brackets and hinges.