Clean fuel injectors?
You can start doing this when the engine is turned off. Just open the engine compartment and then find the location of the fuel injectors. If you are not aware of the different aspects of engines, please feel free to ask people around and get help from people who know this better. Also, make sure that no amount of fuel is pumped right into the engine before doing this. Also, remove the fuel pump, which in turn will stop fuel return. Another alternative is to install tubing, the purpose of which is to connect the fuel inlet with the fuel outlet. Now, get a pressurized solvent and hook it to the fuel injectors. Turn the engine on and start running the solvent right through the running engine. next, you can take out the cleaning supplies by turning off the engine. Later, reconnect the fuel pump as well as the fuel lines. Now, turn the engine on and see if there is improvement and if there isn't any, repeat again.
Why are you getting fuel to your carburetor on your 1986 GMC 15 but no fuel will go through the injectors?
In order to answer this you need to be more specific as to what fuel problem you are having. Is it a fuel pressure problem? or a fuel injector problem. I would suggest you go get the fuel pressure checked to begin with. That can usually tell you if the fuel problem is from the fuel tank to the fuel rail or if the problem may lie in the fuel injectors. A weak fuel pump…