I have a 2000 3/4 ton with the 6.0 where I ran into the same problem from the day I bought it. At times, when I stepped on the brake pedal, the gas guage would go to "E" and say low fuel even when it was full. In fact, the guage would always do it when the tank was above 3/4's full or below 1/4 tank. Several other chevy owner's I talked with said that they had similar problems with the fuel guage reading correctly. The problem came from the the rheostat (variable resistor) on the fuel pump/sending unit's float arm (basically the fuel pump assembly). I replaced the sending unit assembly and it cured the problem (2 years without a problem now).
From people I talk to, they said that the OEM sending unit in the truck was bad from the factory and those model years saw this problem commonly occur.
Friday, January 8th, 2010 AT 9:43 PM