1991 Chevy S10 Pickup

First check for battery voltage. Then make sure you have a check engine light when the key is in the run position. Make sure the fuel pump relay is good. Check to see if there is power on one side of the injectors, if these wires have a short to voltage or ground the injectors will not funtion properly. In this system the injectors are supplied with constant power and ground controls pulse width. In these blazers and s-trucks PCM ground sees to become an issue. In mine I directly routed the system grounds to a metal body panel under the right side of the dash. In my Blazer I swapped out the motors and converted from and automatic to a manual transmission. And another problem I found was when I lifted the dash to install my clutch pedal, I broke my brake light switch. In an automatic the brake pedal switch interups the ses light circuit. If the PCM dosent sense the ses light on the system cannot ground. Good Luck with it, At the time I had completed my second of four automotive level so it took me a bit to figure it out on my own. Once I took my level 3 (electricl) it sunk in alot quicker. Happy hunting, don't get too pissed off.

Have you checked the fuel pump relay?