Burger King Corp. (search) , the world's No. 2 hamburger chain, said on Friday its chief executive, Brad Blum, has left the company after 18 months on the job due to strategic differences with the company's board of directors.

Further details on the reason for Blum's departure were not immediately available.

In a statement, privately held Burger King said its senior management would oversee the business until a new CEO is found. It hopes to make a decision on Blum's replacement by Aug. 1.

Burger King is owned by a private equity group consisting of Texas Pacific Group (search), Bain Capital (search) and Goldman Sachs Capital Partners (search).

Owen Blicksilver, a spokesman for Texas Pacific, confirmed that some meetings with potential candidates have taken place, but he declined to provide further details.

Blum's departure comes just 18 months after he joined struggling Burger King from Red Lobster parent Darden Restaurants Inc. (DRI), where he was vice chairman.

During that time, Burger King changed advertising agencies and revamped its menu, causing sales at U.S. restaurants open at least a year, or same-store sales, to post their biggest gain in four-and-a-half years in May.

But despite the chains' progress, trade publication Advertising Age reported last month that Blum, 50, was on his way out and that Burger King had interviewed potential candidates for his replacement.

In a note to clients following that report, Smith Barney analyst Mark Kalinowski said a CEO change at Burger King would give a boost to rivals McDonald's Corp. (MCD), Wendy's International Inc. (WEN), and Jack In The Box Inc. (JBX).

"It is possible, part of the reason Burger King's market share has declined in recent years is because of a 'revolving door' to the CEO's office," Kalinowski wrote, adding that the chain has had nine CEOs in the last 15 years.

Burger King, which has about 7700 restaurants in the United States, most of which are franchised, last month promoted John Chidsey to president-chief operating officer, North America, after four months as chief financial officer-chief administrative officer.