The Metro Board yesterday reluctantly accepted the only bid it received for diesel fuel to run the bus fleet for the next year.

It is the first time since the energy crisis of 1973 that there has been so little competition in the bidding, Metro officials said. Metro also was forced yesterday to accept the only bid offered on a much smaller quantity of unleaded gasoline for other vehicles.

The Gulf Oil Corp. was the only bidder on both diesel fuel and unleaded gasoline.

"We don't have any choice; we've got to have fuel to run the buses," Metro Board member Francis B. Francois said. Gulf's bid was for 15 million gallons of diesel fuel at 42.66 cents a gallon. However, an escalation clause means the price will rise during the year.

Last year, for example, Metro was paying 38.91 cents a gallon at the first of the year but 43.01 at the end of the year. The rising price of diesel fuel has been an increasing concern to the public transit community nationwide.

Harry T. Smyth, Metro's purchaser, told the board that more than 20 potential suppliers had been solicited to bid on the contract, but that only four major oil companies provide diesel in this area. Those four are Exxon, Shell, Gulf and Texaco.

"The pipelines have been over-loaded," Smyth said. Petroleum products come to the Washington area primarily through the Colonial Pipeline, which is jointly owned by several major oil companies.

"Sometimes, in situations like this, only one company would have adequate capacity rights in the pipeline to move this amount of product," a knowledgeable petroleum source said. It could not be learned if this were the case.

Tom Denmon a spokesman for Shell Oil, said his firm declined to bid because "we're just not taking on any new customers. We've been slowly withdrawing from the fuel oil market on the East Coast." Diesel fuel is a close relative of fuel oil.

Donald Kaplan head of the energy section in the antitruse division at the Justice Department, said "there are a lot of good economic reasons why this could happen that have nothing to do with collusion."

The board asked the Metro staff to report on the efforts made to solicit bids from other possible suppliers.

In other Metro matters yesterday:

The board ordered the staff to survey the street entrance areas around all Metro stations to determine if lighting was adequate. The order came after board members learned from a reporter that there is little outside lighting at the Foggy Bottom station entrance, where a man was beaten and robbed last week. That, and another robbery at the Deanwood station the same night, were the first such incidents in the subway's history.

The board approved a final location for the planned Columbia Heights subway station, on the yet-to-be-built Green Line between Gallery Place and Greenbelt. The station would be beneath 14th Street NW in the vicinity of Irving Street and Columbia Road NW, with entrances at 14th and Irving.

The board approved the transfer of the Brook Mansion from the Metro property rolls to the District of Columbia. The mansion, near the Brook-land Station, has been ordered preserved as a historical landmark. In return, the board will get the Benning Elementary School, an abandoned building near the Minnesota Avenue Station, where more parking and bus facilities are planned.

The board's revenue and operations committee began debate yesterday on regionwide fare increase proposals for the subway and buse in Maryland and Virginia. A number of possible fare formulas will be analyzed in future meetings.