fuse blowing.
If this is a 4.3, check to see if the fuel injector wires are pinched where they go through the collar that surrounds the throttle body. Next ohm out the injectors, there is two, to see if they are within specifications. Somewhere around 12-15 ohms.Also check to see if the wires are rubbing elsewhere in the engine compartment. There might be other things that could go wrong but this is a start.
Let us know how it turns out.