The World Boxing Association ruled today that its heavyweight champion, Mike Weaver, must fight James (Quick) Tillis before Sept. 30 or be stripped of his title.

The WBA gave Weaver and his manager Don Manuel until July 15 to sign for that fight, and said that if Weaver defeats Tillis, he must fight Gerry Cooney within another 120 days.

Manuel, who attended a marathon nine-hour session here today, said he doubted that Weaver, who fights out of Los Angeles, and Tillis, and undefeated professional from Chicago, could agree on a contract now, if ever, "unless somebody goes crazy and offers X amount of dollars, which I don't see anyone going to do."

He said Weaver has already agreed to fight Cooney in late October, a fight that should be far more lucrative than a bout with Tillis.

WBA rules require a champion to defend his title against the No. 1 contender within a year after he wins it. Weaver defeated John Tate on March 31, 1980, for the WBA championship and fought Gerrie Coetzee of South Africa Oct. 25, 1980. Coetzee was not the leading contender.

Manuel's attorney, Franklin Edwards, indicated that if Weaver is stripped of his title, he would probably fight the move in court.