1995 GMC Sierra pick up 5.0 l motor. Motor cranks but does not turn on. I checked all fuses and fuel pump relay and I disconneted the fuel line and opened the switch and fuel came through.and still doesn't start. I poured gasoline in throttle body and it turned on but turned off after gas finished. I tried different computer modules but this did not help. I observed that the fuel injectors don't open and also the fuel pump current is not optimal. What else do you think I should do?

Replace the Ignition Control Module (ICM), located inside the distributor.

I tried to replace the ICM inside the distributer but this did not help. Also the fuse for the fuel pump relay does not have power. Any other suggestions?

Check all under hood and under dash fuses with a test light or multimeter. Turn the ignition switch to ON and check for power through both test points on every fuse--red to fuse, black to ground. On trucks, in Texas, I often have to remove and clean the contacts on under hood fuses and fuel pump relays--corrosion and dirt build-up badly.

If you have an inertia cutoff switch to the fuel pump, reset it. These are most common on Fords, however.

Check the ignition switch for wear, pitting, or melting, if the problem persists. Disconnect the negative. Battery cable first.