2001 Chevy S-10 I got fuel pressure to injectors but inject

I put my truck on a scanner and it said it was the fuel pressure sensor, I got that fix and now nothing shows up on the scanner. My truck start quick with starter fluid. My truck is body drop and the cab been replace. There is pressure to the injectors and with 55k miles on motor they should work. Do u think my computer not triggerin the injectors? Do I need a computer? Or is it true they have to be program and how would I find out if my computer isnt already program? I hate do spend money on something that already works. Can you please, please help me figure out the problem? Your my only hope Thank,
Juan