An ebullient J. Marshall Coleman, buoyed by President Reagan's appearance on his behalf, campaigned through the Washington suburbs yesterday, contending he has turned the corner and predicting victory in his race for Virginia governor.

Meanwhile, his Democratic opponent, Charles S. Robb, charged in Norfolk that Coleman is focusing on racially tinged issues that threaten to polarize blacks and whites.

Coleman told a Northern Virginia press conference: "I really believe this is the week for the momentum to surge in the Coleman campaign." Later, the Republican candidate said in an interview, "We're really within striking range and if we get out our vote and all, we'll win."

Polls published last weekend indicated Coleman still trailed Robb by 9 percentage points. But at a series of stops in the Virginia suburbs and later at a press conference in Bristol, in the southwestern corner of the state, Coleman was aggressively upbeat.

Robb, who is trying to gain the support of both white conservatives and blacks in an attempt to break 12 years of GOP tenancy in the governor's mansion, accused Coleman and some of his backers of raising potentially divisive racial issues during the Richmond campaign rally that Reagan attended Tuesday night. The Democratic nominee, campaigning in Norfolk, said he has rejected suggestions he counterattack because "I'm not going to be the cause for dividing Virginia along racial lines again."

Robb insisted he is not "backing away" from his stands favoring ratification of the D.C. voting rights amendment, making Dr. Martin Luther King's birthday a holiday and setting aside a percentage of state business for minority contractors.

But Robb, the state's lieutenant governor, said he is hesitant to launch a full debate on the merits of those issues, "not only because I might lose votes," but because it could "drive a wedge" between Virginians.

Coleman rejected Robb's charge and said he was addressing questions that Democrats had raised. "There is no issue . . . that wasn't raised first by the Robb campaign" in its pursuit of black voters, Coleman said.

Racially tinged themes came up again last night at a Coleman rally in Roanoke featuring Gov. John N. Dalton and former governor Linwood Holton.

Dalton criticized Robb's stand on the federal Voting Rights Act and postcard registration of voters as well as the D.C. Voting Rights Amendment. He said two D.C. elected senators would cancel out the conservatism of Virginia Sens. Harry F. Byrd Jr. and John W. Warner. "The philosophy of the people of Washington, D.C., is entirely different than the philosophy of the people of Virginia," he said.

That drew applause from the crowd of about 250 but not total enthusiasm. Holton, whose governorship was noted for its moderate racial stands, did not applaud. He said afterward that repeated emphasis of race issues "doesn't bother me . . . it's not my campaign."

Robb conceded yesterday that "a mistake" within his own campaign organization gave Coleman the excuse to attack his stands on racially tinged issues. The Democratic nominee said that black leaders came to him last month and asked for his views on a number of issues that might soothe black concerns about his conservatism. Robb said that in providing his positions, he asked that "three things specifically be excluded" from his appeal for black votes -- D.C. voting rights, King's birthday and business for minority contractors.

Those issues were among several addressed in a letter supporting Robb subsequently distributed in black areas over the signature of Democratic state Sen. L. Douglas Wilder of Richmond. Wilder's letter is being used by Coleman and his supporters -- including former governor Mills E. Godwin -- in attacking Robb's conservativism.

Robb said yesterday he "won't be drawn into crying racist" by denouncing the attacks, although he said in an interview, "I came very close to doing that.

"If I do launch a frontal attack, that's the whole campaign. And every time you generate those passions, you take a step backwards." Debating those questions, Robb said, "would make Virginia look like it was still in the late 19th century."

Robb said he did not know if his stands on the three controversial issues "are a plus or a minus to my campaign, but even if I knew they were a clear plus, I don't know if it would do the state any good" to make them the focus of the campaign in its closing days.

Little could suppress Coleman's high spirits today. When some students at Falls Church High School in Fairfax County booed his call for longer sentences for drug smugglers, the candidate grinned and said, "I guess I lost a few votes on that one."

He began the day shaking hands with commuters at the Ballston Metro stop in Arlington. Unlike previous days, most commuters appeared to recognize him. Some were enthusiastic while others took pains to avoid shaking his hand.

The same was true at George Mason Law School, where Coleman got a generally warm response from students and faculty. A recent straw poll at the school gave Coleman a 58-to-42 edge over Robb.

While Robb was cautious on the question of racial issues, state Del. Robert C. Scott of Newport News, one of four blacks in the House of Delegates, said, "If race-baiting is going to get Coleman some votes, I wouldn't be surprised that that's what we'll hear for the rest of the campaign." Scott said Virginians "ought to be embarrassed by that kind of campaigning" and he predicted they would reject it.

The four-page letter from Wilder distributed in black areas said "the conservative tone" of Robb's campaign prompted him "to make a more determined effort to know where Chuck stands" on issues important to blacks. Wilder wrote that "Chuck Robb has not abandoned us on the key issues that affect the black community."

The letter then outlined Robb's stand on 13 topics, including the three that later provided the basis of an advertisement critical of Robb placed by Republicans in a Danville newspaper.