The continuing gasoline shortage created an erratic pattern of want and plenty at Washington area service stations yesterday. Some stations continued to close early and some reported long lines of customers, but at other open stations the lines had disappeared.

"We've had no lines at all," said Alexandria Exxon dealer Don Youngman. "We've been open since 7:30 [a.m.] and things are beautiful. People are driving by and doing a double-take. They say, 'Hey, you open?' I say, 'Hell yeah, come on in.'"

But some stations on River Road in Montgomery County reported 15- to 30-minute waits this morning.

Meanwhile, Exxon, the largest gasoline retailer in the Washington area with 450 stations here, announced yesterday it was further increasing the amount of gasoline it is supplying to its stations nationwide for July.

Sunoco, Amoco and Mobil - also big retailers of gasoline here - also have announced slight increases in gas deliveries to stations for July.

An Exxon spokesman attributed the new 2 percent increase to "better than anticipated yields from refinery operations" and to high inventories of products caused by low deliveries to customers during June.

While the gasoline supply situation here continues to be better than in past weeks, stations overall continue to be 15 percent or more short of supplies they had a year ago at this time.

It was not clear why there were lines in some areas here and not in others. It appeared that the lines formed in heavily populated ares with comparatively few stations, or along major commuter routes without many stations.

Most state and local officials attributed the general improvement at the stations to the three-week-old system of odd-even rationing and to an easing of consumer fears, as well as to increased supplies.

"We have a stabilized situation," said local American Automobile Association spokesman Glenn Lashley . . . "Motorists have pretty well adjusted to the strict [supply] situation and are pretty well getting their purchasing habits on schedule."

Lashley said he drove through Silver Spring, Wheaton, Falls Church and Alexandria yesterday and saw many stations open. He said he never saw a line of more than 10 cars. Aides who answered the D.C. and Prince George's County gas hotlines said there were few complaints from motorists about long lines.

But some local officials still were trying to find out why the lines formed in the first place.

A group of Northern Virginia officials went to Richmond yesterday to complain to Gov. John N. Dalton that the state has been shortchanging their area when it allocates Virnigia's set-aside gasoline.

The meeting, however, bore a closer resemblance to a tea party than to a debate.

With Lt. Gov. Charles Robb and Attorney General J. Marshall Coleman at his side, Dalton repeated last week's pledge that the state's Washington suburbs would get at least 3.5 million gallons of the state's set-aside gas this month, about twice what the area received in June.

Dalton said the state's energy office already had sent 2.3 million gallons to the area in the first 10 days of July and he said that action already had eased gasoline lines.

Fairfax County supervisors Board Chairman John F. Herrity, the spokesman for officials from six area localities who attended, presented a report contending the area got 13 percent less gas last month than the rest of Virginia and 31 percent less than it would normally receive had there been no shortage.

The Republican county chairman and the Republican governor took turns blaming the shortage on inept management by the Carter administration's Department of Energy.

The meeting's only discordant note was sounded by Kathleen Seefeldt, chairman of the Prince William County Board of Supervisors, who voiced concern that gas lines might return to the area when the end of the month nears and gas supplies grow short.

Seefeldt also raised the specter of possible shortages of heating oil next winter. Dalton replied that U.S. energy officials had assured him this year'ssupply would be slightly above last year's.

after the session, Fairfax Supervisor Martha Pennino said Dalton had increased Northern Virginia's fuel allocation in anticipated of the meeting.

"I think the Governor realized he was holding all the cards today," she said "He'd already done what we asked for."

After the meeting, Herrity praised Dalton but warned, "If at the end of the month we perceive we're not getting our fair share, we'll be back."

In other energy matters yesterday: Dalotn responded to a National Governors Conference resolution and increased truck weight limits to 80,000 pounds. He also increased the allowable lenghts of trucks from 55 to 60 feet. Dalton said the new limits were necessary because of the state's diesel fuel shortage. Maryland Gov. Harry Hughes also raised truck weight limits last week.

Dalton sent telegrams to the state's congressional delegation urging passage of a bill that wouldcommit $1.7 billion in U.S. funds to complete constuction of the Metro subway system and $198 million annually in operating funds. The bill is due to reach the floor of the House of Representatives next Monday. CAPTION: Chart, Daily Gasoline Guide