Fuel Gauge

[silvdur]

Accuracy Inquiry:

2007 NBS 2500 6.6L 35,000K miles

Fuel Tank = 26 gallons
Low Fuel Light comes on after only using 19 gallon, gauge on empty
I'm getting 18.8-20.8 mpg highway

It seems a bit much to have in tank after gauge reaches empty.
Range shows only 50 miles left.

So 7 x 20 = 140 ? not 50

Send me your thoughts of repair/diagnose. Thank You

[EdHale]

My gauge low light would come on when I had approx 6 gallons left which is very close to what you report. I had my original tank replaced with a Titan 52 gallon tank years ago using the same sending unit and now the low fuel light comes on with approx 10 gallons left.

[Kennedy]

I guess it depends if you want to risk running to down to a point of sucking air or not. Think of it as a motorcycle. Main tank runs until low fuel light comes on then you are on reserve. How far do you push it on reserve? Remember the tank is about 48" long and 12" wide so 5 gallons does not put much depth in the tank.



Add to that you have a recirculating system that produces a lot of heat. Having additional volume in the tank helps to act as a heat sink. For this reason alone I do not advocate running below 1/8 tank for extended periods of time especially in hot weather.

[CoyleJR]

The light coming on early is probably a good thing in disguise. It will keep you from running with a minimum amount of fuel in the tank. I have a 100 gallon auxiliary fuel tank in my truck bed that keeps my primary tank full at all times. The large amount of fuel in the truck tank cools the hot returning fuel. I suspect that is possibly a contributing factor why my LBZ truck at 216k miles still has the original injectors and does not throw the dreaded P0087 code. I would suggest always keeping at least half of a tank of fuel especially in hot weather. The bottom line is don't worry about the light.