GMC Troubleshooting Questions? Ask a Mechanic for Answers
I am very sorry for the long wait
if you unplug the big fuel injector connector on top of the fuel injector then with the key ON do 8 out of the 16 terminals in the connector you unplugged show 12 volts ?
if 8 do show 12 volts then connect a test light with the test light clip to battery 12 volts and when cranking it over do the OTHER 8 blink terminal your test light bulb when cranking it over ?
if NO flashing light with the test light clip connected to 12 volts then this comes down to either a bad ignition module or bad computer
isnce it runs if you add fuel that is all that is left o cause no injector pulse so there is not fuel getting into the engine
with it having spark that is all it can be
that is what i said if it has spark an NO injector pulse it is the ignition module or a bad computer
was the known good computer reprogrammed to your trucks VIN number ?
another computer will not work unless its programmed to your trucks VIN number