A Falls Church High School sophomore was found dead in his bedroom yesterday after he apparently tried to get high by inhaling fumes from a can of Scotchgard fabric protector, a Fairfax County police spokesman said.

Robert Messick was a go cart fan who had competed in races all over Virginia with his father, winning the state championship in 1978. Three weeks ago, his friends said he began to experiment with Scotchgard, which is used to water-proof and spot-proof upholstery. It was the first time he had tried any form of drug, they said.

His mother, Beverly Torbert, found his body shortly after midnight yesterday, slumped on the floor of his bedroom at 2907 Meadow La. in Falls Church, with a plastic bag over his head and an empty can of Scotchgard next to his body.

Small amounts of the product were found inside the bag, according to police spokesman Warren R. Carmichael. An autopsy to determine the cause of death, however, may not be completed for several weeks.

"He had done this no more than two or three times before," Torbert said yesterday. "He didn't know what he was doing. The police kept saying that he was obviously inexperienced with this."

The death of the 16-year-old Messick was the first reported in Fairfax involving Scotchgard, a product manufactured by the Minnesota Mining & Manufacturing Co. in Minneapolis from silicon resin, carbon dioxide and a powerful solvent.

"It's also known as methyl chloroform," said Franklin Griffith, an expert in the study of poisons for the 3M Company. "In my five years in toxicology, I have never heard of anyone attempting to use this product in that fashion."

Tests performed at 3M showed that methyl chloroform impaired coordination, caused headaches and resulted in loss of equilibrium if it were inhaled in large doses. Griffith said a state of "drunkenness" was produced in the victim as the chemical attacked the central nervous system.

The product label carries detailed warnings about its dangers and instructs users to spray fabric only in well ventilated areas.

"It results in something called myocardial depression," said John Bell of the federal Consumer Product Safety Commission. "In laymen's terms, it's a heart attack because the heart can't contract and pump blood."

"The effect of this chemical isn't really to be considered toxic. It works through oxygen depletion and a disruption of heart rhythms," he said.

Bell said only one other death has been recorded as resulting from inhalation of trichloroethane, the powerful solvent in Scotchgard. A 22-year-old New London, Wis., man died after inhaling the chemical through a plastic bag in 1975.

Messick's mother said, "his friends have been standing outside the house all day. They just can't believe it. They said he was as straight as anyone could be."

"He had a good outlook on life, and felt like he had everything going for him. He's been racing all over Virginia with his father. But he got along really well with Bill (Torbert), his stepfather, too," she said.

Messick's teacher, however, told his mother and stepfather that Robert "was under a 'severe' amount of peer pressure from his friends. Robbie wanted everybody to like him, and if there was any real problem, it was peer pressure."