When College Park Exxon dealer Steven Yates ran out of gasoline Monday afternoon, he draped the hoses over his six pumps like dead snakes, their nozzles hanging useless. By noon yesterday, he had turned away 150 customers.

As a result, business jumped 25 percent yesterday at C.F. Mangene's Exxon nearby. Mangene was selling unleaded gasoline so fast that he cut off its sale at noon in order to stretch out supplies.

Shortages at Exxon stations may come sharper and sooner this month than at other stations, industry sources said, because. Exxon waited until March 5 to announce it was curtailing supplies to dealers.

Thus its dealers pumped gas during the first week of the month as if there would be no curtailment. Because most other oil companies announced curtailments earlier, demand at Exxon stations leaped 35 percent during the first week of this month as customers switched.

Yates had pumped 30,000 gallons of his allocated 40,000 gallons for the month by March 7, when he learned officially of the curtailment. A week later he was out of gasoline.

"If I'd known at the beginning of the month, I could have saved gas," said Yates. As it was, he curtailed hours, closed Sunday and raised prices 4 cents a gallon as soon as he learned of the curtailment, but people kept coming. "Demand was the same."

Yates' station is near the busy intersection of U.S. 1 and Greenbelt Road. Nearby Shell, Texaco and Homoco dealers said their supplies have been somewhat curtailed, and they already are or will soon be closing Sundays and otherwise curtailing hours.

All voiced concern that publicity Would trigger a run on the service stations. Dealers and officials say that this would cause a "false shortage,' draining the underground storage at stations to fill everyone's tanks.

Officials say that the public should trim consumption by 5 percent to 10 percent. Then, they said, there shouldn't be lines at the pumps or major disruptions.

Exxon has 450 stations in the Washington area, making it the leading supplier of gasoline here with a claim to 20 percent of the market.

An Exxon spokesman said yesterday that about 1 percent of its stations in the region are out of fuel and about 5 percent "will be in trouble" with less than half the supplies they need.

Yates, who bought his station a year and a half ago and built it from 8,000 gallons of sales a month to 80,000 today, is one of those. He was selling 40,000 gallons a month a year ago -- and that's all he can receive under the allocation rules.

About 25 Exxon stations in Virginia are out of gasoline, according to Willian Kalberer of the state Office of Emergency and Energy Services. No other stations are out of supplies, Kalberer said.

In Maryland, Energy Policy Office Director Donald E. Milsten said about 1 percent of the state's 3,500 stations are short of gasoline. He said he doesn't know how many are out entirely.

None is out in the District, according to Richard Bottorff of the Office of Emergency Preparedness.

These officials control an emergency reserve -- called a "set aside" -- amounting to 3 percent of all gasoline sold in their jurisdictions. The oil companies must have this much in reserve to provide at official direction to places where it is needed.

Officials can order this reserve to be used for these items, in this priority: defense, agriculture (includes professional fishermen), emergency services, energy production, sanitation, telecommunications, passenger transport, cargo freight and mail hauling by truck, aviation ground support vehicles, and finally industrial, commercial, government and social service uses.

So far this month, District and Maryland officials have not used their set-aside power. In Virginia, 35,000 gallons has been ordered delivered to Nelson County for its school buses and to a private construction contractor who needs it on a project where 200 jobs are at stake, according to Kalberer.

Milsten, the Maryland official, said the set aside could not be used to help dealers like Yates. He said Yates should apply to the federal government for help.

Thomas Wieker of the U.S. Department of Energy's office of hearings and appeals said that dealers like Yates can apply for an "exception" giving them a higher allocation.

If a dealer can show he's being driven out of business or is suffering exceptional hardship he can get an exception, Wieker said.

"Our job is to separate the (dealers) who really have problems from the general desire (all dealers have) to get more gas," he said.

"My place is for sale," Yates said yesterday. He said he can't afford to stay in business.

Mangene said he would raise prices in order to decrease demand.

"It's going to snowball into something," he said with a shake of his head. "Usually people might get five or 10 gallons. Now they're filling the damn things right up to the top."