I wish they would fix it because it is annoying. I don't think it was programmed that way intentionally. The 48 gallon tanks aren't having this problem. My F150 had a 36 gallon tank, and the gauge on it was accurate. I was excited to see that they finally put a 34 gallon tank in the SWB Super Duty, thinking I could enjoy the extended range of a large tank similar my F150. Much to my disappointment, if you go off the gauge, its like having a 29 gallon tank, and I have to fill up more often. This makes the bigger tank seem rather pointless.

 

Curious, for those with the 34 gallon tank, does the gauge read correctly and just the MTE is wrong? Or is the fuel gauge wrong too?

 

Fuel gauge is wrong too.

 

I think its just a calibration issue. It should be a simple fix, albeit expensive if Ford issues a TSB. In the end it all comes down to $.

 

This may sound dumb but has anyone tried to shine a bright light on the side of the fuel tank to see if they can see a fuel level or any sign of how much fuel might be left. Just a thought.

 

The 34 gallon tank is too small? How did you feel about the previous 26 gallon tank on the short bed? That's a massive increase.

It sounds like you guys are getting all 34 gallons, but the gauge is ultra-conservative on DTE.

Here's a question: when the DTE reads "0 miles" how does the gauge look? Is it on "E" ? Or somewhere near 1/16 to 1/8 of a tank?

 

Just answered that a few posts up- fuel gauge as well as my Edge Insight CTS both read around 5%- 10%. I think this was at 15 miles to empty

 

Good question. I have a 3.55 E-locker, Short Bed, Crew Cab

 

Thanks. Gauges typically read conservative as well...sounds like the gauge may read slightly less conservative then DTE?

 

I am gathering some data for this subject. I agree it is annoying. Granted, it is easily dealt with but annoying nonetheless. I have made some notes on my last few fill-ups, jotting down the MTE and the amount of fuel dispensed. I only have four data points so far but it's a start. Trying to find our at what mileage past zero MTE is the actual 34 galling dispensing point. So far, with my limited data, I calculate that point being 74 miles past MTE. See my initial chart below. Note that the RED data point is the calculated 34-gallon point. I will gather more data on a few more fill ups, then I'm going for 70 miles past zero if the data confirms.

An old professor of mine once told me..."There is only one thing you can trust absolutely, and that's math".

 

Have to say I'm impressed with your effort on this. It sounds like for sure the capacity is in the tank, but the calibration is *ultra* conservative. Hopefully there is no Ford engineering reason why it needs to be this way. Obviously, some fuel is needed in the bottom of the tank to cool the lift pump (I believe this pump is located in the tank for 2017; previously it was in the fuel filter housing on the rail)...maybe the shape of the 34 gallon tank requires more to be left in it...but that would make the extra capacity somewhat pointless.

 

Thanks T-man. I will also offer if anyone gathers some data from their 34-gallon diesel fill-ups I will add those to my analysis. Just post the MTE showing (negative if it is past zero MTE) and the fuel dispensed at that fill-up. The more the better.

T-man, or others, I have a question. I am hoping the fix can be a calibration adjustment of the fuel level system by a tech at the dealer. Is the fuel level determining mechanism a mechanical one (floating arm) or conductive?

 

Very interesting data. I also wonder if the conservative fuel gauge might be intended to insure that when the tank just reads empty, that indeed fuel can be pulled regardless of attitude of the truck. It would be a bummer if you took it to -10 MTE, then climbed a hill, and flamed out on the way up due to the placement of the fuel pickup.

In any case, I would prefer that the gauge reads zero when you are very close to using all the remaining available fuel, regardless of attitude. I generally do not trust MTE, as that is a calculation based on fuel left in the tank, and average fuel mileage. Once again, when climbing under load, fuel mileage is much lower than the average, so that in that scenario, MTE can indicate more miles available than there is fuel available at that higher consumption rate.

 

Nice chart....but it only took two fill ups in mine to target exactly how big the reserve was...and how much off the computer is in these trucks. First fill up...I went to 30 miles until empty. It took 27 gallons even. That leaves two gallons...one for each of my 15.0 mpg that my gauge was showing...therefore...5 gallons reserve. Next time I took it to Zero miles until empty...this time it took 29 gallons....leaving exactly 5 gallons reserve. Both of the fillups show that the computer is leaving 5 gallons of diesel in the tank. That's my chart....

 

Like others have said, the 48 gal tank is spot-on accurate. You might get 10 miles - then again you might get 10 feet.
I went over my MTE by about 5 before I found a gas station. It took 47.55 gallons to fill her up.
Just a word to the wise.

-ysgi