In this paper we present a method for the selective blocking and subsequent filling of metals into photonic crystal fibers. We derive a model which can predict the necessary duration of the filling process. With a melt and pump procedure we obtain single micron sized metal wires adjacent to the PCF core with aspect ratios of about 10^5. We will present a semi-analytical solution of the dispersion relation of a cylindrical metal wire in a dielectric and discuss the results with respect to surface plasmon polaritons. By comparision with finite element simulations of an unfilled photonic crystal fiber we will show that a coupling between a core mode and surface mode is possible at specific phase matching wavelengths. Furthermore, measurements of transmission spectra will be presented to confirm the mode coupling between the fundamental core mode and the surface plasmon polariton of order m = 3.