Kevin Fouser's kick into the low left corner of the goal on the ninth round of a shootout last night gave the United States a 9-8 victory over Honduras in a semifinal game of the World Youth Soccer championship at RFK before 4,703.

Both teams had scored once in overtime after the regulation game had ended in a scoreless tie. Both then made four of five shots in a shootout round of five and each team successfully converted three more shots before Fouser's goal.

The final score is arrived at by awarding a point for each goal scored and a point for each successful shootout kick.

After Fouser beat goalkeeper Cesar Roberto Martinez, Honduras missed a chance to tie when Juan Contraeras' right-foot kick bounced off the cross bar, setting off a frenzied celebration of the rain-soaked grass.

The Americans gained the right to play in Sunday evening's final against Mexico, which won, 4-3, over Canada in the evening's first game. The final will be played at Giant's Stadium in East Rutherford, N.J., as a preliminary to the Washington Diplomat-New York Cosmos game. Both will also advance to the 1981 Junior World Cup Championship in Australia.

John Stollmeyer gave the United States a 1-0 lead in the first 10-minute overtime after 83 minutes of play. Honduras' Jorge Montenegro tied the game at 1-1 with only 4 1/2 minutes left in the second and final overtime.

The rain destroyed game strategy for both the U.S. and Honduras with the sopping grass preventing almost any dribbling, cutting or sharp passing. The usually high-stepping, stylish Honduran strikers and midfielders were forced to dump the ball into the American zone, watch it plop dead in a puddle, and then piddle around at midfield before the U.S. repeated the action.

Almost the entire first half was played at midfield with the U.S. -- usually Stollmeyer -- winning the middle-of-the-field battles and controlling the snail's pace.

The only good scoring opportunity of the first 40 minutes came when two Honduran defenders slipped allowing three red-shirted Americans to surround goalkeeper Martinez. But he managed somehow to reach out with both hands and grab Jay Ainslie's low-to-the-ground header. The shot, on a dry surface would have skipped into the net before the keeper had a chance to react, but in the water, the ball slowed considerably, enabling Martinez to get to it.

In the second half, when the rain subsided and field conditions improved, both teams put on impressive end-to-end offensive rushes, with Honduras outshooting the U.S., 17-14. As forwards flashed in the goal box in front of each net, goalkeepers Martinez and American Craig Scarpelli dazzled the small but vocirerous crowd with acrobatic saves to maintain the scoreless tie in regulation.

Honduras should have had a 1-0 lead in the game's 60th minute when Jay Ainslie shoved a poor pass from the corner to Scarpelli, coming out to the left of the American goal. Mexico forward Juan Espinoza intercepted it and passed to Jorge Montenegro, whose shot went far over the empty net.

In a spectacular display of goalkeeping, Scarpelli tipped a blast off the foot of Victor Romero into the crossbar. As the ball deflected off the pole high into the air, Scarpelli drove out and gathered it in as two Honduras forwards swooped in like vultures.

U.S. forward Kevin Fouser missed an equally exciting empty-net opportunity at 73:53, on a diving kick that rolled wide to the left.