Fossett will try to take off in his Virgin Atlantic GlobalFlyer aircraft from the Kennedy Space Centre on Wednesday between 6.40am and 7am local time.
"The fuel leak is fixed and we believe the worldwide wind pattern is acceptable," said Mr Fossett.
"I hope to be flying in the morning."
The weather at Cape Canaveral, Florida had been problematic from as early as Monday, with organisers initially saying the forecast for the launch on Tuesday was 'marginal, but satisfactory'.
Fuel loss fear
Jon Karkow, in charge of the airplane's fueling, said the fuel leak was due to an untested new part that did not seal properly.
Fuel loss is something that worries Fossett's team: during his first record-setting flight around the world completed in March 2005, Fossett reached his final destination in Salinas, Kansas with less fuel than anticipated.
As planned, Fossett's newest adventure would take him 41,978 kilometres in approximately 80 hours, 1,126km farther than the 1999 around-the-world balloon trip by Brian Jones, a Briton, and his Swiss partner Bertrand Piccard on the Breitling Orbiter III.
That would also beat the distance record set by Dick Rutan and Jeana Yeager in their nine-day, non-stop trip around the world without refueling aboard the Voyager aircraft in 1986.
That trip logged a total of 40,212km.
In March 2005, Fossett flew around the globe alone for 67 hours, two minutes and 38 seconds without stopping and refueling in a trip across 36,989km.
Multi-record breaker
The thrill-seeking Fossett, who has set records in sailboats, gliders and hot air balloons, said his next feat "will take me to the very edge of my ability and endurance."
After the takeoff, Fossett plans to fly eastward in a route that will vary according to the wind, probably passing over central Africa, Saudi Arabia, India, China and southeastern Japan before traversing the Pacific and reaching Mexico.
He then plans to fly past Cape Canaveral and go over the Atlantic a second time before landing at Kent International Airport in Britain, near London.
The Virgin Atlantic GlobalFlyer was designed by aviation pioneer Burt
Rutan, creator of SpaceShipOne, the first private manned rocketship that travelled into space in 2004.
Rutan also designed the Voyager flown by his brother Dick in 1986.
The special aircraft is 13.4 metres long and has a wing span of 34.7m.
It weighs a total of 9.98 tonnes, including eight tonnes of fuel.
Fossett will fly at an altitude of 13,700m and at a cruising speed of 470kmph, in a trip funded by British billionaire and renowned thrill-seeker Richard Branson, the head of the Virgin Atlantic airline.
To prepare for the long flight, Fossett has been on a diet that includes eggs to limit his bathroom needs.
He will consume energy drinks during his three-and-a-half-day trip.
Fossett will take several five-minute naps during the flight. The cockpit is equipped with an alert system to rouse the pilot if he falls asleep.