hi guys my fuel pump died so i put a second hand one in but now it is back firing under load can you help the car starts perfect and idles perfect

Check that the hose in the fuel tank hasn't split or the hose clamps are tight enough. I suggest that you change this hose with new clamps. I know it's a pain to remove the pump again and check, but i've had 2 seperate cars do this to me. If you want to check without removing the pump again, put a fuel pressure guage in the rail and start the car. It should read around 40psi. Any lower and you could have a fuel leak in the tank.

P.S. The second hand pump could be faulty too. Should put new one in there not that expensive.