"The launch is scrubbed, and we'll come back in tomorrow and see how the ... sensor behaves," launch director Mike Leinbach said on Friday.
It was the latest in a string of launch delays for this Atlantis mission, an 11-day trip to the International Space Station to undertake construction operations.
The new launch time, set for Saturday at 11:15 am (1515 GMT, or 0115 Monday AEST), came after discussions with the Russians over possible conflicts with their planned September 18 Soyuz flight to the ISS.
The National Aeronautics and Space Administration said the faulty fuel sensor on an external fuel tank was detected during fuelling operations early on Friday, and after lengthy examination of the problem and discussions by mission officials, they decided to put off the launch.
Friday's launch scrub came after the team of six astronauts had already climbed aboard the shuttle and about an hour before the scheduled lift-off.
NASA spokesman George Diller had said there were two options: continue the countdown, since the sensor, which measures the tank's hydrogen level, is one of four and only two are needed to operate the shuttle safely; or delay launch for 24 hours, empty the fuel tank and examine the faulty sensor.
"We judged it was more prudent to delay the launch and review the data," Wayne Hale, the shuttle program manager, said at a news conference.
Engineers emptied the external tank of nearly two million litres of hydrogen and liquid oxygen, worth more than US$500,000, to see how the four gauges function when it is empty and full.
If the faulty gauge remains defective and the other three function normally, a launch will be possible Saturday, Mr Hale said.
"It's very difficult to pinpoint the origin of the problem," acknowledged Leroy Cain, the launch integration manager of the space shuttle program. "But we don't believe we have a generic issue."
Weather apparently would not be an issue. Lieutenant Kaleb Nordgren, a US Air Force meteorologist, predicted an 80 percent chance of favourable conditions for a launch on Saturday.
If Saturday's launch is also scrubbed, Mr Hale said the earliest next launch would be in late September, if restrictions on a night launch are lifted, or at the end of October.
A problem with a fuel cut-off sensor, which shuts down the shuttle's engines when the hydrogen tank is empty, preventing an explosion, delayed the launch of the shuttle Discovery for several weeks in 2005.
Atlantis had originally been scheduled to blast off on August 27, but was delayed first by lightning and the effects of Tropical Storm Ernesto, and then by technical problems.
On Wednesday, a blastoff was delayed twice because one of the three fuel cells providing electricity to the shuttle malfunctioned.
After an extensive review, NASA managers opted to proceed and said the problematic fuel cell presented no serious risk to the shuttle and crew, since two fuel cells alone can provide enough power to accomplish the major goals of Atlantis's mission.
If it does launch finally on Saturday, it will be the shuttle's first construction mission to the half-finished ISS in nearly four years.
Atlantis is to transport a new 16-tonne segment with two huge solar panels that will double the station's ability to produce power from sunlight and ultimately provide a quarter of the completed ISS's power.
Officials said it will be the most complex work ever undertaken at the nearly eight-year-old space station and noted that the next few missions will only get more difficult.
The agency plans to undertake 16 shuttle missions to complete the complex assembly of the space station by 2010, when the three-shuttle fleet is set to retire.
After the space shuttle Discovery returned safely in July from a mission aimed at improving safety, NASA declared it was ready to resume construction of the ISS, which is central to US ambitions to fly humans to Mars.
Three lengthy spacewalks are planned to install the solar arrays.