March 7, 1981

Equipment breakdowns in yesterday morning's rush hour delayed nearly all 95,000 of the Long Island Rail Road's commuters, including 2,000 who were stranded under the East River for three hours after a train stopped in a tunnel. Thousands of frustrated passengers disembarked during unscheduled stops at the line's Hunters Point station in Queens and headed to subway stations and bus stops for the rest of the trip to Manhattan. But at least as many, having been advised by the railroad of ''a 30-minute delay,'' stayed on board and suffered average delays of an hour and a half to two hours. ''Just about everybody was affected,'' said Alexandra Zetlin of the railroad's public-relations department. The systemwide delays came near the end of an especially difficult winter on the nation's largest commuter line. Railroad officials attributed a rash of breakdowns and canceled runs in December and January to bitterly cold weather. Last summer, chronic airconditioning problems plagued the line.

The Reagan Administration announced today that it had decided to sell additional military equipment to Saudi Arabia as part of a policy of halting a ''serious deterioration'' in Western security interests in the Middle East and Persian Gulf. Contending that there is a ''growing threat'' in the area from the Soviet Union, the Administration said it had decided, over the objections of Israel and many members of Congress, to provide equipment to improve the range and fighting power of 62 F-15 jet fighters purchased by the Saudis. The F-15 Eagle built by McDonnell Douglas is an aircraft designed primarily as a fighter that would have ground-attack ability as well, the State Department said. It was first delivered to the United States Air Force in 1973. Sales to Israel and Saudi Arabia were approved in 1978. Japan will begin receiving F-15's next year.

The possibility that schizophrenia might be caused by a mysterious substance in the blood, and cured by removing it with the hemodialysis technique used in kidney disease, is sustaining a continuing scientific debate about the merits of this costly, dangerous therapy in treating mental illness. A new research report published last week in the journal Science challenges the view that dialysis treatments help schizophrenics, but proponents of dialysis argue that the study is inconclusive and that more research is needed. Dr. Herbert Wagemaker, director of psychiatry at the University of Louisville Hospital in Kentucky, says that he has several patients in research projects who have been ''doing very well for eight or nine years on maintenance dialysis'' treatment for schizophrenia. ''There are only three or four days a year when their symptoms break through and require medication,'' he said. Studies at other institutions have yielded mixed results.

In the Gulf of Fonseca, a Salvadoran patrol launch halts a fishing boat to search for arms.

Continuing large increases in energy prices resulted in a rise of eight-tenths of 1 percent in producer prices in February, the Labor Department reported today. The department also said that the national unemployment rate edged down last month, to 7.3 percent of the labor force, after two months at 7.4 percent. But top Government economists said the Administration still expected a weaker economy in the spring and summer and a marked unemployment rise. (Page 13.)