LAMPO JUNCTION, UTAH, AUG. 27 -- A redesigned shuttle booster sat silent on its stand today while engineers worked furiously to recover from the effects of a leaky fire hose and some minor electronic glitches on what was supposed to be a morale-boosting test firing.

After three delays in four hours, the test was postponed until 3 p.m. EDT Saturday.

Nosed horizontally into a bunker of 5,000 cubic yards of concrete and steel to block its forward thrust, the 14-story test rocket, loaded with 1.1 million pounds of propellant, twice came to within 15 seconds of firing.

Officials from the National Aeronautics and Space Administration and Morton Thiokol Inc., manufacturer of the booster, said they were frustrated by the test delay but stressed that the problems were caused by the failure of ground support facilities and not related to the booster itself.

"This is not a test failure," said NASA space flight chief Richard Truly. "It's a failure for us to get the test off on schedule."

More than 500 people, including a congressional delegation, top space officials and the news media, gathered on the desert sands in a viewing area about 9,000 feet from the test stand on the slopes of the Wasatch Mountains.

Cars loaded with spectators lined the roads outside the Morton Thiokol plant where the boosters are made for what was supposed to be the first full-scale test of the redesigned shuttle booster that caused the Jan. 28, 1986, Challenger disaster. The accident killed the crew of seven and grounded the shuttle until at least June of next year.

Although this is one of a series of planned full-scale test firings, it is widely viewed as being the most important as a psychological symbol for the space program.

The testing schedule is so tight, officials said, that everything must work correctly if the June 1988 launch target for the next shuttle is to be met. But, Truly said, "We have about two weeks flexibility in the schedule" before delays of this test would result in a change in the other tests.

The test had been scheduled to begin at 3 p.m. EDT, but the tension-laden countdown ended abruptly when test countdown coordinator Roger Williams said, "Abort the motor."

The initial delay was caused by a leaky hose that is part of a water-deluge system designed to cool down the rocket casing after the test blast so that it can be reused. A connection broke between the fiber hose and a metal water line, officials said.

In addition, an electronic sensor on the thrust vector control, the booster's steering mechanism, was giving no reading. It was repaired.

The test was delayed a second time about 4:30 p.m. because the computers were "out of synch" as a result of the first delay and had to be recycled, officials said.

In the third delay, an automatic shutdown occurred because of another problem with the thrust vector control turbine. Engineers could not determine what the problem was and at this point, around 6:30 p.m., the firing was postponed.

Engineers in the control bunker had been at their stations since 5 a.m. After the second delay, a delegation led by Truly, J.R. Thompson, head of the Marshall Space Flight Center, and top Thiokol officials went to the bunker and told the team, "We're in no hurry. We want to do it right," Truly said.

The NASA and Thiokol team members "wanted to keep going. They were incensed that we thought they might be tired," Truly said.

Many of the officials on hand have been through thousands of tests and many delays. "Testing boosters is just not easy," said NASA propulsion official Russell Bardos.

"It's ironic that in a high-tech world, you still have to deal with basic plumbing," said a congressional aide who flew out from Washington for the test.

A design team from Morton Thiokol and NASA has made radical changes in the critical booster joint that leaked and caused the Challenger's destruction. They added a third rubbery O-ring seal, a metal "capture feature" to lock the joint members more firmly and heaters to avoid the ill effect of cold weather that contributed to the Challenger accident.

Charles Locke, chief executive officer of Morton Thiokol, said the test would be "the sight and sound of America returning to space," and the excitement was palpable as the countdown proceeded under a dazzling blue dome of mountain-rimmed sky.

Thompson, whose center manages the booster rocket program, paced back and forth, kicking gravel and grinding a small stash of rocks in his fist. "These will be sand by the time this test is over," he said.

"I didn't sleep a wink last night," said Jack Kapp, manager of engineering design for Morton Thiokol.

Some 25 miles from the nearest community, the Thiokol plant is deliberately remote because of the highly explosive fuel it handles. Inside a trailer complex set up for visitors and news media, posters lined the wall. They picture the crew of the next shuttle flight and bear the legend: "Morton Thiokol Space Div. The STS-26 crew is counting on you."