1994 s-10 blazer help???

i have a 1994 s-10 blazer with a 4.3 vortec .first ran out of gas fine put in gas started drove away , an hour later i went to start it and no start fuel pump was not running, i replaced pump with a new one i had from a 92 blazer and it now runs but wont start. there is pressure at the intake, and spark.
also noticed that all of a sudden the battery is draing quickly i charge it full and it is dead in 20 minutes . i have no clue what to even look for or what would cause this from a fuel pump being changed ?
any help would be greatly appreciated
thanks

What is the fuel pressure reading?

I'd try another battery if you have one available that you know is good. A bad cell in the battery can seem to charge but drops off very quickly when loaded.

thanks for the advice both you guys were right
first the fuel pressure was not enough with the pump i put in so i changed it and the battery went bad i guess from the tow truck having the 4 ways going while he towed it to me
but anyhow it is perfect again thanks again
greatly appreciate all the help

You are welcome and thanks for posting back how it went.
Good Luck
MT