The Department of Transportation yesterday bought $3 million in stock from a Washington minority-owned venture capital firm to help it provide loans or equity capital to railroad-related minority businesses.

Fulcrum Venture Capital Corp. sold 3,000 shares of preferred stock with a par value of $1,000 to the government through the Federal Railroad Administration's Minority Business Resource Center.

Those funds, along with $2 million from Fulcrum's parent company and $2 million from a sale of preferred stock to the Small Business Administration "will give Fulcrum $7 million in available resources which, if fully leveraged by SBA, would give us maximum investment potential of up to $25 million," Fulcrum President Steven Lilly. i

"This transaction and others like it represent investment, not loans or grants," said deputy Transportation secretary William J. Beckham during a press conference yesterday. "The sums are not large by federal standards, but they will loom large in the future" of minority business.

The funds lent to the minority- or women-owned firms can be used for plant expansion, equipment and working capital in railroad-related businesses, Transportation Department officials said. As part of the agreement, Fulcrum will pay a 3 percent cumulative annual dividend to the Transportation Department, Lilly said.

So far, the Transportation Department has invested $9.6 million nationally in seven minority-enterprise small business investment corporations from New York to Los Angeles.

Fulcrum was started in 1978 by the Opportunity Funding Corporation and Cooperative Assistance Fund of Washington. As a MESBIC, it's purpose is to provide long-term debt and equity capital to small businesses owned by economically or socially disadvantaged entrepreneurs.

In another development, the Commerce Department yesterday said it will make available $12 million to direct, low-cost loans to minority-owned automobile dealers that are suffering from the current slump in automobile sales.

The 8 1/4 percent interest loans and SBA loan guarantees with interest rates of up to 14 1/2 percent are part of President Carter's program to aid the auto industry announced earlier this week.

Commerce Department officials said yesterday that minority dealers have insufficient equity capital and rely more on debt than other dealers.

At a conference last May on problems of minority automobile dealers, industry experts said that the Ford Motor Co. lost 50 percent of its black dealers last year and 15 of the 39 auto dealers on Black Enterprise magazine's top-100 minority-owned companies dropped from the list.