How to change fuel pump 1998 s10 4x4 Chevy blazer?

The fuel pump is located inside the fuel tank. I believe that your model year also has the fuel level sending unit as part of the pump and the whole thing costs about $300 to $400. I have replaced inside-the-tank pumps before and they are not all that difficult on a vehicle as new as yours. Buy a "Chiltons" or a "Haynes" (the latter is my preference) for about $20. The procedure is too lengthy to spell out here and the manual gives photo too (I have mine in front of me as I write).