Rep. Joseph L. Fisher (D-Va.) and GOP challenger Frank Wolf picked up last night where they left off two years ago, staking out predictably opposing positions for voters to choose from in Northern Virginia's 10th Congressional District.

Fisher, a liberal Democrat, defended his record in Congress without praising that of his party's leader, President Jimmy Carter, while the conservative Wolf blamed Carter for the nation's economic woes and said Republican presidential standard-bearer Ronald Reagan would lead a "new majority" down the road to a beefed-up defense policy and a balanced budget.

If there were few surprises in the initial debate between Fisher and Wolf, whom the three-term incumbent defeated by about 8,000 votes two years ago, there was enough spark between the rivals to suppress yawns among the 100 or so people who turned out for the Arlington County Civic Federation debate at the Woodland Hill apartment House cafeteria.

Both Fisher, an economist, and Wolf, a lawyer, agreed that inflation was a major issue, but they offered different ways to attack it. Fisher said a balanced budged is "unrealistic in 1981" but he favors the idea when it could be accomplished without putting too many people out of work. Wolf made no such reservation in his all-out support for equalizing federal income and expenditures.

The large number of federal workers who live in the 10th District, which includes all of Arlington and Loudoun counties and the northern half of Fairfax County, got attention from both men too.

Wolf said he opposes any attempt to include government employes in the Social Security system, while Fisher hedged, noting only that "I blocked the steamroller [attempt] to sweep federal employes" into the system in recent congressional sessions.

Noise pollution, in the form of jet traffic at National Airport, also was targeted by both the incumbent and the challenger as a priority issue.

Both men advocated shifting some of the airline traffic to Dulles Airport, which also is in the 10th District.

Wolf, 41, whose feisty verbal assults on Fisher in 1978 prompted Fisher to complain about Wolf "yapping at my heels," said he would encourage greater use at underutilized Dulles by extending Metrorail service to the airport, using the medial strip of the Dulles Access Road as the right-of-way.

Wolf would help finance the project by exempting Metro construction from federal regulations that require paying workers prevailing union wages.

Fisher, 66, who describes himself in campaign literature as "a steady hand, a quiet voice," was cautious about the Metro extension, saying only that he has cosponsered legislation to study its feasibility.

If those issues were not enough to give voters a clear choice, there were a couple of old standbys on which they took flat-out opposite positions: Fisher favors the Equal Rights Amendment, Wolf opposes it; Wolf opposes allowing federal workers' health insurance to pay for abortions, Fisher favors it.