The Fairfax County Board of Supervisors voted early today to postpone a decision whether to keep its 19-year-old promise never to extend Fullerton Road, the main road through Fullerton Industrial Park, to Rolling Road on the west.

Supervisors Joseph Alexander (D) of Lee District and Marie B. Travesky (R) of Springfield, chief combatants on the issue, were anxious for a decision. But Republican supervisors Nancy K. Falck of Dranesville and Thomas M. Davis III of Mason urged the board to take more time to consider the matter.

Board Chairman John F. Herrity (R) appointed a bipartisan committee to study the issue and report; no time limit was set.

Alexander, whose district includes the industrial park and borders Rolling Road to the east, led the battle to change the county's master plan and allow the road to go through. He held that dramatically changing traffic conditions in the park, which has only one access, justifies reneging on the board's 1964 promise.

Travesky, whose Springfield district includes the residential area to the west, headed the fight to persuade the board to keep its word and block construction of an additional 150 feet of roadway. She maintained that Rolling Road cannot handle the industrial park's traffic and that the county shouldn't introduce industrial traffic into residential communities.

More than 50 people who live or work near the industrial park addressed the board at the public hearing. Hundreds of persons looked on, frequently interrupting the testimony with cheers or jeers. The process took four hours.