I've got a 2001 Silverado 1500 4.8l that's doing the same thing. I've tried resetting the security, and even by passing the security. Checking the fuel filter and pump tomorrow. My security light stays lit even after pulling key out of ignition and key fob isn't working. Tried to resync the key fob but my truck won't go into sync mode. I put the key in ignition, held the unlock button on driver door for about 5 seconds then turned ingition from off to on without starting it 2 times. The pressed lock and unlock button for over 30 seconds on key fob but never synced. Grr