Maryland Cup Corp., which is expected to be acquired by the Fort Howard Paper Co., yesteday reported profits for the quarter ended June 30 of $12.3 million ($1.17 per share) compared with earnings of $9.2 million (90 cents) in the same period a year earlier.

Sales for the company's third quarter, were $188.5 million compared with sales of $183.9 a year before.

The company's president, Samuel Shapiro, said the improved results reflect both a reduction in operating costs and somewhat higher sales.

Shareholders are scheduled to vote Aug. 31, on the previously announced agreement under which Fort Howard would acquire Maryland Cup, the nation's largest manufacturer of paper and plastic food service products.

Crown Central Petroleum Corp. of Baltimore announced net income for the second quarter of 1983 of $3.9 million (54 cents a share), compared with a net loss of $2.9 million (52 cents) for the same period in 1982. Sales for the second quarter were $353.2 million, compared with sales of $416.8 million a year ago.

The second quarter results were also an improvement over the first quarter of 1983 when the company reported a net loss of $10.5 million ($1.74) on revenues of $348.5 million. Maryland Cup Earnings Rise In 3rd Quarter

Maryland Cup Corp., which is expected to be acquired by the Fort Howard Paper Co., yesteday reported profits for the quarter ended June 30 of $12.3 million ($1.17 per share) compared with earnings of $9.2 million (90 cents) in the same period a year earlier.

Sales for the company's third quarter, were $188.5 million compared with sales of $183.9 a year before.

The company's president, Samuel Shapiro, said the improved results reflect both a reduction in operating costs and somewhat higher sales.

Shareholders are scheduled to vote Aug. 31, on the previously announced agreement under which Fort Howard would acquire Maryland Cup, the nation's largest manufacturer of paper and plastic food service products.

Crown Central Petroleum Corp. of Baltimore announced net income for the second quarter of 1983 of $3.9 million (54 cents a share), compared with a net loss of $2.9 million (52 cents) for the same period in 1982. Sales for the second quarter were $353.2 million, compared with sales of $416.8 million a year ago.

The second quarter results were also an improvement over the first quarter of 1983 when the company reported a net loss of $10.5 million ($1.74) on revenues of $348.5 million.