The Fairfax County Board of Supervisors last night defeated a proposal to ask county voters to approve selling $25.56 million in bonds this spring. The supervisors indicated they prefer to try their luck in more economically stable times.

The board voted unanimously to consider holding the referendum in November.

If approved by county voters, the funds would be used to build four new fire stations, improve the storm drainage system, expand one of the county's three garages and complete several other planned projects.

Two years ago, Fairfax voters rejected a similar county bid for the sale of $16 million in bonds, $4 million of them for the construction of new fire stations and $12 million for storm drainage.

Urging the board to move back a proposed March 25 date for the board referendum, Supervisor Joseph Alexander (D-Lee) said, "the timing of the effort leaves me concerned, given the general financial situation of the country and the attitude of people today. I think we need these things but I don't want to jeopardize our chances."

Supervisor Marie B. Travesky (R-Springfield) stressed the need for greater citizen involvement in the bond effort, pointing to a public hearing in which only three citizens spoke. "I believe you can sell any bond referendum if it is properly prepared," she said.

Approval of the bond sale would result in no additional cost to taxpayers, according to James P. McDonald, the deputy county executive for management and budget.

Because the bonds are sold at interest rates for lower than the county can get on its investments, McDonald said, "It obviously would be cheaper for the county to sell bonds on every swing it wants to build."

McDonald estimated that the 20-year bonds, if approved, would be sold at an annual interest rate of 5 1/2 percent, while the county is averaging 15 percent on the investments.