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TO THE MAX
11-15-2007, 07:43
I recently had just below a half tank of fuel. When the truck got restarted later in the day it show empty and the light came on (40 miles to go). As I drove the truck around the gauge moved up a little and the low fuel light went out. I went to fuel up to be sure no one hijacked my fuel and it took 18 gals. Then the gauge read just below full and now it shows I used 3 gals but sits at 3/4 of a tank. For short it looks like it is reading on the low side. Does not make sense.
trbankii
11-15-2007, 08:42
Your sig line doesn't give a year for your truck, but it is possible for the float in the fuel tank to become water-logged (fuel-logged? oil-logged?) and no longer "float" properly. Other possibilities are wiring or associated electrical issues.
carco
11-17-2007, 14:28
Probably the fuel sending unit. We have seen many sending units bad before they should. Ferd, Dodge, GM, Toy. bob..........
Thumper Pilot
11-17-2007, 20:39
I just had a new sender unit put in my tank, it would never read higher than 5/8ths full - works like new now.
TO THE MAX
11-19-2007, 10:39
I have a 2005 3500 crew cab. The digital milege countdown (mile to go) on the dash coincides with the the gauge (low reading). Does this narrow the options? I suppose this would be something that would have to go to the dealership? If not does anyone know a part number for this?
DmaxMaverick
11-19-2007, 10:53
I have a 2005 3500 crew cab. The digital milege countdown (mile to go) on the dash coincides with the the gauge (low reading). Does this narrow the options? I suppose this would be something that would have to go to the dealership? If not does anyone know a part number for this?

That would almost certainly confirm the tank sender being the problem. The PCM (or BCM) reads the tank level as a %, and calculates mileage accordingly. If your PCM sees the tank level at X, then it will calculate the "miles to go" accordingly. You can read the tank level % with a scanner, and it should be consistent with the gage. My tank sender is on the fritz, only showing 1/4 tank at full, but is linear with fuel usage (1/2 fuel used is showing about 1/8 on the gage). The PCM is seeing/reporting the fuel level consistent with the gage.
Turbo Al
11-19-2007, 14:17
Mine (2001) has done this several times. Start it up in the morning and it reads dead empty even though I know it has fuel in it. In my case it is so infrequent that it is not worth worrying over.
Al