99 GMC Starts then Dies.

I have a '99 GMC pickup with the 5.3 Vortec that has an intermittent
starting problem. The engine will not restart under various conditions.
After long crank times and jump starting the engine will start. On other
occasions the engine will restart and then die as soon as the ignition
switch is returned to the run position. I have ruled out the fuel pumps and
the relay. There are no diagnostic codes that are tripping the MIL lamp. I
don't have any way of retrieving the codes from an OBD2 system. The only
item that I inspected that seemed to resolve the start/die problem was the
airflow sensor. After inspecting the airflow sensor the engine started and
continued to run. This may have just been a coincidence as I didn't find
anything noticeable problem with the sensor. Any help with this problem
would be greatly appreciated.

Dale Greep

I had this problem with a 96 Chevrolet PU. The wiring harness on the
fuel pump (inside the gas tank) had gotten hot and semi-melted so that
it wasn't making good contact all the time.