LOOKING BACK, it was not the best of times for a border crossing. But one group of Americans, unaided by hindsight, dared the Central American night in the fall of 1978. Leaving Honduran hills for northern Nicaragua on a darkened road, they encountered flashing lights.

Certain they faced ambushed by bandits, and unable to see that what lay ahead was a police car, the Americans sped off. The police gave chase and fired their guns. One American was hit, badly wounded in the arm.

That night the duty officer at the American Embassy in Managua, Nicaragua, received a frantic phone call. "Our friend's been shot," the caller said. "They want to take off his arm. You've got to get him out of here." But the caller refused to give his name or the location of the small village clinic where they had found first aid. Nor would he permit the duty officer to speak with the doctor in charge. He hung up.

By telephoning medical facilities along the travelers' likeliest route into the country, the embassy finally located the wounded American. The next day, a counsular official drove more than 100 miles to check his condition and ensure his health and safety.

When the injured man's friends left the country for the United States, essentially abandoning him, the embassy found on its hands one American badly needing expert hospital care. Eventually he returned home, intact. The embassy had seen to his treatment and then convinced his American employer to hire a medical evacuation plane to fly him out.

Around 10 million Americans traveled abroad last year. More are expected this year with increasing numbers venturing to out-of-the-way places in Third World and Eastern Bloc countries. Incidents such as the one described are becoming commonplace.

Foreign jails hold 1,600 Americans. Many of those are drug offenders, despite vigorous warnings from the State Department that drug laws overseas are not more lenient than those here and in many cases are extremely severe. An estimated 10,000 Americans will die overseas in 1979. An untold number will become destitute and require more than million in emergency loans. About 25,000 will report lost or stolen passports. Others will drop out of sight, prompting calls from worried relatives. More will fall ill and require medical attention that sometimes isn't readily available.

Most will turn for help to the U.S. State Department, in the person of an American consular official.

Cut-rate air fares and charters are attracting growing numbers of elderly and young tourists, prime candidates for trouble, says Alan Gise, director of overseas services in the State Department's Bureau of Consular Affairs. So far this year, six Americans required emergency medical evacuation from the People's Republic of China. Three others have died there.

Other duties require increasingly more attention. The London bureau, said Gise, handled about 200,000 visa requests just a couple of year ago. One million are expected this year.

With such demands and other pressures, consular officers, empowered to aid in many ways Americans who encounter difficulties abroad, may not always deliver the kind of service the American traveler expects of his overseas representative. Many Americans have complained of a State Department they say is negligent and uncaring.

If you are one of those who expects the U.S. government to bail you out of every jam, "forget it Charley," says Barbara Paley. "You ain't got nothin'. It's really changed my ideas about traveling. I feel much less secure."

Paley is administrative assistant to Rep. James Ambro (D-N.Y.). In 1976, Ambro and his staff investigated the strange disappearance of one his constituents. The investigation lasted nearly a year. It uncovered more than anyone had anticipated.

Jane Bissell of Long Island, N.Y., disappeared in October of 1976 near a mountain village of Ecuador called Banos, about 70 miles south of Quito, the capital. In Quito she had split up with her traveling companion, Australian Geraldine Crouch. They agreed to meet in Banos a few days later.

When Crouch arrived in Banos, Jane Bissell was nowhere to be found. In her room at the pension, where she had arrived Oct. 3 and had paid for three days lodging in advance, were all of her belongins: clothes, camera, hiking boots.

On Oct. 7, Crouch returned to Quito to report at the U.S. Embassy that the 35-year-old Bissell, an experienced traveler, hiker and mountain climber, had disappeared. She traveled to and from Banos once again in search of her friend. Finally, on Oct. 21, she wrote Bissell's parents.

"I am afraid this is the most difficult letter I have had to write. I only hope that you have been contacted by the American consul in Quito as they promised and this is not the first indication you received. . . ."

The Bissells have not seen or heard from their daughter since.

Ambro discovered that Jane Bissell was not the only American missing in the Andean mountains of Ecuador. Delilah Yoder, a social worker from Bethesda, Md., disappeared with a friend, James Herschberger of Philadelphia, just six months earlier.

Were the disappearances of Jane Bissell, Delilah Yoder and James Herschberger somewhow related? Could the State Department have prevented the occurrences or done more to assist in finding the apparent victims? Their families have spent thousands of dollars and, in the Yoder case, devoted their lives to the search. They say the State Department did little to help.

"After more than a year," said David Yoder (Delilah Yoder's brother) at congressional hearings held in 1977, "we believe our efforts to learn the facts of this case have been severly hindered by the ineffective and unresponsive attitude of the State Department. . . . We believe the available resources within our own government have not been properly or fully utilized. We believe it is possible that our feelings and perhaps even human lives are being sacrificed for 'diplomatic reasons' and are possibly being used as 'pawns in someone's political game.'"

In May of 1977, about 25 parents of Americans imprisoned in Bolivia held a prayer meeting at the main entrance of the State Department to protest what they considered a lack of U.S. government action. More than 30 Americans spent up to three years in Bolivian prisons on drug possession and trafficking charges without being brought to trial.

"There was not way out," said William Farmer of his son, Richard, jailed without trial for more than two years. "You couldn't get them out through the legal system because the law had been written with the help of the U.S."

Farmer said it was not until after a change in administrations that he found officials in the State Department sympathetic to his son's plight.

The lesson to be learned from such cases, consular officials say, is that there is only so much the State Department can do, or will do, for troubled American travelers. Tourists must be more cautious.

Says one former consular official: "The United States government is not in the business of making sure you're not inconvenienced. It's in the business of making sure you do not become an embarrassment to the U.S. government."

Barbara M. Watson, assistant secretary of state for consular affairs, concedes that consular officers can't administer to every case as efficiently and as compassionately as the department would like.

"Hour after hour, day after day," Watson told Congress, "consular officers are intimately involved with troubled human beings. We are just not beginning to question what happens to officers who work intensely with others, learning about their psychological, social, economical, or physical problems. Ideally, consular officers retain objectivity and distance from the situation without losing their concern for the person they are working with. However, they may not always be able to cope with this continual emotional stress. . . ."

In the last year, the State Department has taken measures to improves services for travelers. On the home front, it has reorganized the Citizens Emergency Center in Washington to increase the Welfare and Whereabouts section staff from three persons to five. It discontinued the duty-officer system, where officers took calls for help at home, and placed an officer on duty at the center until midnight. The Counsular Affairs office recently gained its own press office to inform potential travelers of possible dangers.

Still, Consular Affairs is understaff. About 250 U.S. Foreign Service posts represent the United States around the world. More than 160 have two or just one full-time consular position. In some cases, one American official is responsible for all service-related duties in an entire country.

Consular officers are sometimes hampered by more than their workloads and physical and emotional stress. Their activities are circumscribed by treaties, international law, U.S. foreign policy, local laws abroad and occasionally by U.S. statutes.

The State Department denied the Yoders information it had gathered about their sister. In classic Catch-22 fashion, the government cited the Privacy Act as prohibiting it from divulging information without permission from Delilah Yoder.

The State Department cannot investigate disappearances, unless invited by the local police, without violating the host country's sovereignty.

Sometimes demands of American travelers border on the ridiculous.

One former high-ranking consular official, who served in both Europe and Latin America and asked not to be identified, related the case of one 80-year-old man who roamed the countryside on his bicycle molesting young boys. Another, who had a seasonal job in New York, yearly flew abroad during the off season to visit relatives. Each year when it came time to fly back he claimed poverty and asked the embassy to be repatriated.

In one instance, a traveler walked into the consular office complaining that someone was sneaking into his hotel room at night and rearranging the fillings in his teeth. He said he spent half a day putting his fillings back in their proper places. The consular official advised him to put glasses filled with water around the room to see where the intruder was entering. When that didn't work, the official suggested he go back to New York, where he would be safe. He did.

Though some consular officers may prove especially helpful, Americans should not expect unusual treatment, such as loans, free taxi service, travel arrangements or free shipment of bodies.

What you should expect is:

Help in contacting relatives or friends if you become destitute, or repatriation (one-way flight tickets are issued on loan) and subsistence loans until your check from home arrives.

Assistance in finding medical treatment or an English-speaking physician.

Aid in times of civil unrest or natural disaster.

Notification of relatives in the case of your demise, and arrangements for remains. (Remember that many areas do not pratice embalming. Often, bodies must be buried immediately.)

Visitation from consular officials if you are arrested and some assurance that your right under local and international laws are not violated.

Help in locating missing persons.

Issuance of a new passport if yours is lost or stolen.

Even if you made plans months in advance, it is unwise to travel if you develop health problems. Take a doctor's certificate if you must carry medication. Leave an itinerary and passport number with relatives so you can be located in an emergency. And if you have any doubts about the country you are traveling through, discuss your plans with the local U.S. consulate. If someone you know needs assistance abroad, you can reach the Citizens Emergency Center at 202/632-5225. CAPTION: Illustration, no caption, by Robert Barkin - The Washington Post