Alvan Adams' two free throws with 33 seconds left broke a tie and the Phoenix Suns beat the Kansas City Kings, 81-76, tonight to deadlock their National Basketball Western Conference semifinal at three games each. The deciding seventh game will be played Sunday in Phoenix.

With Scott Wedman finding the range on his jump shots after missing 15 of 19 shots the first three quarters, the Kings battled back to go ahead four times in the last period. They had trailed by 10 points three times in the first half.

But after teammate Ernie Grunfeld's jumper from the side with 48 seconds left tied the score at 76, Wedman deflected a shot by the Suns' Dennis Johnson only to have the ball fall into Adams' hands. He was fouled by Grunfeld.

Adams made the two free throws, and that was enough to enable the Pacific Division champions to go home even after trailing the surprising Kings, 3-1, in the best-of-seven showdown.

"I was lucky to get the rebound," said Adams, a slender 6-foot-9 center. "The ball just fell straight down in my hands. It had to be an air ball for me to get it. (Kansas City center) Sam Lacey was having a good game, and I wasn't rebounding. I happened to roll off Sam, and there I was."

Phoenix Coach John MacLeod felt his reserves made the difference against Kansas City, which was operating with only nine healthy players.

"The Kings were on the offensive boards all night," MacLeod said, "and they kept charging. Johnny High came off the bench in the first half and helped. Nothing will be easy for us, even if we are going home. Sunday's game should be tremendous."

Kings Coach Cotton Fitzsimmons, who played his regulars most of the way, said, "I just watched the films. I wanted to see why Adams and not one of our players got that rebound. That might be the key play of the series."

Johnson led the Suns' balanced attack with 17 points, one more than collected by jump-shooting guard Walter Davis. Truck Robinson had 15 and Adams 14 as the Suns outshot Kansas City, 47.5 percent to 38.3. Wedman had 19 points, 10 in the second half, and Reggie King had 18.

The Kings, outrebounding the Suns, 47-39, were able to control the tempo, putting the clamps on Phoenix's fast break. Lacey had 12 rebounds and King 11, while Robinson had 10 for the Suns, who twice were assessed technical fouls for playing a zone defense.

"We don't play a zone defense," McLeod said. "That's against the NBA rules. Ask any of our players."