I started this thread bec Iíve been wondering two things:
How do others handle the fuel tank reserve capacity issue when the warning light comes on?
Should I have gotten the diesel due solely to the increased driving range you get?
The problem is that the SMB has the 46 gallon tank but the fuel gauge is inaccurate bec itís calibrated for a 35 gal tank. And when the fuel warning light comes on (E on the gauge) there is still lots of fuel remaining.
Does anyone else have the same experience??
It sounds like TwoVans warning light is accurately calibrated to his 46 gal tank.
As I showed in my first email, the real capacity in my SMB fuel tank is about 44.6 gallons. Letís call it 45 gal for now. The OEM tank was 35 gal, and according to my local Ford Truck Center, the reserve capacity when the light comes on is 2 Ė 3 gal. But that is not documented on paper and is nowhere in the manual. I was thinking it might have been a 5 gal reserve, which more closely matched what I measured when I filled up as described below.
Anyway, when the warning light comes on, the calculations on paper say there is about 12 Ė 13 gallons remaining [45 - 35 + (2 or 3)]. I had said in my first email that there are about 17 gals remaining but that is wrong.
I should have said 15 gallons. I had determined this on road trips by filling up when the fuel warning light came on, and topping off. It consistently took about 31 Ė 33 gal to fill, depending on my highway mpg ... which was pretty consistent at 10 Ė 11 mpg.
I mistakenly thought I had a 47 gal tank, and I used 32 gal typical to arrive at 15 gallons remaining (47-32). So, I would use 10 mpg and thought I could safely go about another 150 miles, +- before needing to refuel.
However, bec the fuel warning light comes on when there is still about 1/3 of a tank remaining, the warning isnít actually very useful. Therefore, it is important to have a good sense of the MPG for the type of driving being done, so one can make good estimates of distance to empty.
So, my new estimate for highway driving or combined when the fuel warning light turns on:
45 Ė 32 = 13 gallons remaining ... and at 10 mpg I can go about 130 miles.
Pretty much I know I need to fill up within 100 miles to play it safe.
To summarize the conditions for the above MPG and fuel capacity:
2010 E350 RB SMB 4x4 V10 6.8L gas engine, 17000 miles on SMB
I donít tow anything, no roof rack (do have solar panel), no awnings or ladders, do have Aluminess rear and front with WARN winch
I drive 62 Ė 65 mph on level highways, 50 - 55 mph steeper grades
The 46 gal tank is actually 44.6 gal ... Round up to 45 gal
Highway driving typically averages 10.5 Ė 11.5 mpg ... USE 10 mpg for highway and combined
All city driving (rare, but helps approximate all off-road driving, also rare) typically averages 8.5 Ė 9 mpg ... USE 8 mpg
Range of diesel V. gas:
From researching the forum back in 2009 it seemed that 14 Ė 15 mpg was the best AVERAGE to expect from an SMB 4x4 diesel engine not towing anything.
Using 14 mpg and 45 gal capacity = 630 mile range. That is way better than 450 miles with my V10.