MIAMI (AP) _ Jerry Ruenheck announced Monday that he's resigning as president and chief operating officer of Burger King Corp., but intends to open up his own franchises after leaving the fast-food chain at the end of May.

''I look forward to becoming a franchisee ...,'' Ruenheck said in a statement released through Burger King. ''I am now moving off to rekindle my entrepreneurial fires.''

Ruenheck will be replaced by Jay O. Darling, 36, currently executive vice president of operations, said J. Jeffrey Campbell, Burger King's chairman and chief executive officer.

Darling has been with Burger King for 14 years, starting his career with as an assistant restaurant manager.

According to Campbell, Darling will become president of Burger King USA, the company's domestic subsidiary, starting Tuesday. Ruenheck will remain as corporate president until May 31, the end of the company's fiscal year.

Ruenheck, 45, joined Burger King as a management trainee in 1969, moving up the executive ranks over the years. He became president of Burger King USA in 1980 and two years later was named to his present post.

Burger King, a wholly owned subsidiary of Pillsbury Co., is the second largest fast-food chain after McDonald's Corp. Burger King and its franchises operate 4,000 restaurants worldwide.

Ruenheck is expected to open several Burger King franchises in Florida, said Steve Finn, a spokesman for the Miami-based company.

Finn said it was not unusal for departing executives to start their own franchises. ''They end up leaving because they want to go out and open up a restaurant of their own. It's an entrepreneurial instinct,'' he said.

Between now and June, Ruenheck will work on new programs and strategies to help improve the corporation's working relationship with Burger King franchises, the company said.

''No one in Burger King has more credibility with our franchise community than Jerry Ruenheck,'' Campbell said.