Where is the fuel pump relay located on a 1995 chevy blazer

The electric fuel pump is located inside the fuel tank.

On the s10 model the relays are generally inside the glove box, there should be two or three of relays under a cover on the upper left side. The diagram on the cover will tell you which one is for the fuel pump (I think center of the three). If the horn works you can switch it with the fuel pump to test.