How to rebuild a seized engine?

I replaced the engine on a 1999 chevy silverado and it was cranking but won't start cause of no spark found out it was the ignition control module replaced it and then it tried to start up.then died out then tried to start it again and then it seized up. A few days later got it freed up n put spark plugs back in it was cranking put fuse back in for fuel pump it tried to start up and it almost started then it seized again how would i go about fixin this problem can the gas be causing it to get stuck it seems to seize everytime i put the fuse back in for the fuel pump