The Metro board is expected this morning to approve the inauguration of Sunday sunway service in September and a package of fare increases for all subway riders and for Maryland and Virginia Metrobus riders.

The board has twice delayed voteson the final service and fare package for fiscal 1980 to see if it could build a unanimous consensus for Sunday subway service, which is supported most vigorously by the District of Columbia.

A check with key board members yesterday shows that there are five solid votes for Sunday service out of six on the board. Unanimous votes are soughton items that cost Metro money because each jurisdiction contributes from its general revenues to Metro's operating deficit. Sunday service is expected to add $800,000 to Metro's $120 million deficit in fiscal 1980.

Some details remain to be worked out on the fare package, but its basic outline appear to be in place. Today, during rush hour, the subway costs 40 cents for the first three miles and 8.5 cents for each succeeding mile. The Farecard machines figure the fares.

Beginning July 1, the subway during rush hour will cost 45 cents for the first three miles and 9.5 cents for each succeeding mile.That means that the rush hour fare from Silver spring to Metro center would increase from 80 cents to 90 cents; from National Airport to Metro Center would go from 55 cents to 60 cents; from New Carrollton to Metro Center would go from $1 to $1.15.

Rush hour is defined by Metro as from 6 a.m. to 9:30 a.m. and from 3 p.m. to 6:30 p.m. on weekdays. The off-peak subway fare of 50 cents for all trips will remain the same. The offpeak fare is charged on Saturdays and federal holidays and will be charged on Sundays if Sunday service is approved.

There will ne no change in bus fares for riders who board and get off within the District of Columbia.

However, in the suburbs, the basic boarding charge will go from 50 cents to 55 cents during rush hour. Additionally, there will be a 5-cent increase in the zone charge for buses that cross from D.C. into Maryland or D.C. into Virginia. The outer suburban zone charges will remain the same.

Transfer charges will be imposed on riders going from the subway to the bus. Previously, the subway transfer had been free for one zone on the bus. Under the new structure beginning July 1, the rider must add 10 cents to his subway transfer to board the bus, plus any zone charges during rush hour.

Metro will continue its policy of requiring two full fares when changing from bus to subway.

Metro's three two-week passes would be sold for the same price and thus would represent a genuine savings for the first time instead of just a convenience.Additionally, the $10 D.C. base pass, which presently has a rail value of $5 plus unlimited bus value, would have its rail value increased to $6.

Sunday subway service would begin in time for the Redskin season in September and would be limited to eight hours each Sunday, probably from 10 a.m. to 6 p.m. Metro inaugurated weeknight and Saturday service in the current fiscal year and both have drawn more riders than Metro predicted.

During the past week, with the area suddenly energy conscious, Metro's rail ridership, shot up an average of 10,000 a day over the previous week.

The only negative vote for Sunday service probably will come from Francis B. Francois, Metro board and Prince George's County Council member. Prince George's has said that it can afford no more Metro subsidy than it already has budgeted because of the tax-limiting amendment voted by county residents last November.

"What I'll probably do," Francois said, "ask that the Sunday question be separated from the fare issue, and we'll go from there." Francois and other area Metro board members have said they need the new revenue the fare package is expected to produce.