The Bullets got their first look at Truck Robinson in a Phoenix uniform tonight, but what really caught their eyes was the sight of enemy baskets popping in with uncanny efficiency to beat them in the fourth quarter.

Although onetime Washington stalwart Robinson contributed 10 second-half points to the Sun' 119-108 triumph, he wasn't nearly as important as all those open jumpers his teammates refused to miss in the late going.

The contest was tied as late as 4:02 of the fourth period, 101-all, before the Suns went on a spurt in which they made their last seven shots and four of five free throws.

Robinson had only two of those points, taking a backseat to seven from Paul Westphal, who had 32 for the night, and five from Walter Davis, who totaled 26.

Phoenix has won eight of 13 games since Robinson came over from New Orleans to supply the kind of rebounding power the Suns lack against strong clubs like the Bullets.

But board work didn't give them their first success in four games against Washington this season. Instead, it was the crisp passing and fine shooting which always had characterized this team from the start of the season.

Robinson, however, does serve one important purpose against the Bullets. He occupies the full attention of Elvin Hayes, who has made a career out of overwhelming Sun big forwards.

Hayes, who usually plays well against his former teammate and constant critic, was hindered by foul problems and a running battle with referee Mike Mathis, who wound up calling technicals on both Hayes and Coach Dick Motta before the game ended. Hayes finished with 12 points and 13 rebounds; Robinson countered with 16 and 10.

The Bullets were quite willing to blame Mathis for the defeat, their second in six road games on this long eight-stop trip.

With Phoenix ahead, 105-101, Mathis called Larry Wright for a back-court foul but no one heard the whistle above the crowd noise and the Washington guard, who had stolen the ball from Davis raced in for a layup.

Instead, Davis was awarded two free throws at the other end and made both. Washington never came closer than five the rest of the way.

Mathis, however, had little to do with the Suns' offensive execution down the stretch. With Robinson on the bench after picking up his fifth foul, Phoenix got more movement in its offense and started finding the open man while the Bullets failed to react quickly enough.

Alvan Adams, the center who was not expected to play because of an eye injury, put Phoenix ahead for good, 103-101, on a jumper that would have made any blurry-eyed shooter proud.

A Westphal bomb around two misses by Bob Dandridge and Davis' pair of free throws put the Suns in control. Then Robinson came back in to help on the boards and limited the Bullets to one shot each time down the court.

Motta's technical, converted by Westphal, ignited a 5-0 burst moments later and Phoenix could celebrate its first victory over Washington in more than a year.

Dandridge had been instrumental in keeping the Bullets in the game through 44 minutes. His 30 points, on 13-of-27 shooting, supplied the only consistency his club could muster, although Charles Johnson had a fine second half until tiring midway through the fourth period.

Motta elected to finish the game with a back court of Wright and Phil Chenier, keeping starters Johnson and Tom Henderson on the bench. But neither reserve could cope with the taller and stronger Westphal.

The Bullets had taken a 59-52 half-time margin on the strength of a 10-2 outburst midway through the second quarter that included some good play from backup center Dave Corzine Dandridge had 18 of his points before intermission, mostly on perimeter jumpers against the guarding of Davis.

But Robinson wasted little time in the third period drawing the Suns back into the game. He pumped in eight points in the opening four minutes of play to put Phoenix up by two and the clubs were never separated by more than five points until the last part of the last quarter.

The loss didn't harm Washington's Atlantic Division lead, however. Philadelphia lost again, this time at Cleveland, so the Bullets maintain a five-game bulge going into Friday night's contest at Golden State.