We have searched for evidence of Y production in 3.5 million hadronic Z decays collected by the L3 detector at LEP in 1991-1995. No signals are observed for the decay chain Z → YX; Y→l + l - (l = e,μ), therefore upper limits at the 95% confidence level are set on the following Z branching fractions: Br(Z → Y(1S)X) < 5.5 10 - 5 ; Br(Z → Y(2S)X) < 13.9 10 - 5 ; Br(Z → Y(3S)X) < 9.4 10 - 5 .