91 c2500 won't turn over

Check to see if when someone is turning the key to the start position, that there is power on the small wire down at the starter solenoid. If there is not, check the starter relay, then it may be with the ignition switch, clutch safety switch, or even the neutral safety switch.

Try jumping the starter relay if u stand on the tire pull out starter relay get wire make sure key is on then touch top right prong to bottom left prong at same time truck shud then turn over and start if not make sure the fuel pump is coming on u shud hear it if u dont then grab the thick set of wires closest to the motor push them in toward the fuse box and push up u shud hear the fuel pump if not keep moving wires until u do the jump the starter relay