Fairfax County teachers, angry at the county's refusal to grant a 9.4 percent pay raise next year, voted yesterday in a dawn rally to perform only work for which they are paid.

The job action, unprecedented in Fairfax, was approved overwhelmingly by an estimated 4,300 members of the Fairfax Education Association, the professional organization representing most of the county's 7,000 teachers.

FEA members vowed to stop volunteering for unpaid activities outside the classroom, such as acting as sponsors for clubs and field trips, and said they will start grading papers during working hours rather than evenings and weekends.

The impact of the decision was unclear yesterday. FEA president Bob Hicks told the teachers to refuse requests from principals or administrators to "do something" outside their regular 7 1/2-hour work day. But Hicks warned that if FEA members are instructed to perform such tasks, they should "do it under protest."

Hicks said the teachers should be careful not to be accused of insubordination, for which they could be fired.

County school superintendent S. John Davis said he did not know what effect the teachers' protest will have on the 130,000-student system. "I would think the majority of our teachers will not do anything to impede the progress of students," Davis said.

Davis and the county board of supervisors were targets of a no-confidence vote at yesterday morning's rally, an action he said he found "discouraging to say the least. I'm disappointed that I would be blamed for decisions that are beyond my authority."

Last month the 1,200-member Arlington Education Association voted a similar measure censuring school superintendent Larry Cuban in a dispute over teacher salaries.

Hicks said yesterday the Fairfax teachers "no longer accept that [Davis] is working for them. There is a strong feeling among educators in the county that the board [of supervisors] doesn't understand their needs."

The Fairfax County school board adopted a budget proposal on Feb. 8 that included a 5.15 percent raise for school employes including teachers, who said the proposal fell far short of meeting cost-of-living pressures in Northern Virginia, the Fairfax supervisors approved the increase in a lengthy meeting on Monday.

The teachers had sought a 9.4 percent raise, which they said they need to live in the affluent county where the median family income is $28,500. The average teacher salary in Fairfax is $18,500 a year.

Board of supervisors chaairman John F. Herrity said yesterday the board's decision is final. Herrity, who has three children in county schools, said, "I care about teachers. I also care about good government."

Several teachers interviewed after yesterday's one-hour rally said they plan to grade papers and make lesson plans during the school day. "I normally spend 10 hours on weekends grading papers," said Nancy Larsen, a fourth-grade teacher at Mount Eagle Elementary School. "Now the kids and I will grade them together."

A proposal at the rally for a stronger job action, such as a sick-out, was voted down. Some teachers interviewed said they would doubted a work-to-the-rule protest would be effective.

High school sports, student newspapers and class yearbooks will not be affected because sponsors for those activities are paid, Hicks said.

The teachers' decision received a mixed reaction from students. "I'm glad they're protesting," said Pam DeCarlo, co-editor of the Annandale High School newspaper which supports the job action. "I think they're underpaid."

Others said they were concerned about upcoming activities such as senior proms.