I need instructions on changing a manual feul pump

Disconnect the tank side fuel line from the pump and stick a bolt, spark plug or whatever you have into the hose end to keep fuel from leaking out. Use a flair nut wrench to disconnect the line for the carburetor at the pump. If the pump has a third line (return) block that off as well. Remove the pump from the block, then remove the plate that goes between the pump and block. Glue the pump gasket to the pump, remove the gasket material from the plate and block. If you have a block/plate gasket with the new pump, glue that to the plate. You will find a steel rod in the block. Put heavy axle grease on it, re-install it and have someone turn the engine by hand (not with the starter) while you push the rod into the engine. stop turning when it is at the point where it is the furthest in. The grease you put on it should hold it in position. If there was no plate gasket, use silicone sealer on the part and bolt it back on the engine block. Then, put the pump in place, making sure that the arm is under the rod and the pump is square with the plate. Install both bolts finger tight (use a long socket as an aid) then tighten the bolts, alternating sides so it does not shift to one side. Re-attach the lines and you are finished. Many times after replacing the pump a bit of debris will go into the line and get into the filter so if you have problems starting the engine, replace the filter in the carb inlet. If the engine was running before you changed the pump likely it won't need to be primed but if the engine did not start you can puur a very small amount of fuel into it to get it started. After starting, check your work for leaks.
Good luck!!

Click this link and it will explain the procedure in detail on a small block Chevy which I assume you have. http://www.classiccarauto.com/impala/how_to/replace_chevy_fuel_pump.shtml

Disconnect the fuel (have a round object the size of the inside diameter of the line so you can plug it off) and unbolt the pump from the block. Notice how the arm slides out. When you reinstall the new pump make sure the pump arm goes under the cam shaft or it will not work. Clean the old gasget off of the block before reinstalling the new one. reconnect the fuel. The engine may have to turn over several times before fuel pressure is suffecient to start the engine.