I have a 2011 F-250 with the 6.7L and my issue is that the fuel gauge and the fuel used on the TripA/B does not correlate. Have roughly 4500 miles on it and this has been going on since day one.

When I fuel the tank and let it stop via the dispenser auto shut off, the dash gauge reads over F, roughly the thickness of the indicator needle. I have a 26.0 gallon tank.

As I drive along, the gauge does begin to indicate the fuel level however; the quantity remaining does not correlate with the fuel that has been used.

For example:
When the gauge indicates F, 1.5 gallons used
When the gauge indicates 3/4, 5.0 gallons used; should state 6.5 gallons was used
When the gauge indicates 1/2, 11.0 gallons used; should state 13.0 gallons was used
When the gauge indicates 1/4, 16.5 gallons used; should state 19.5 gallons was used

When I fill up at just under1/4, it will only take 17.5-ish gallons. Each time, every time.

I have taken it to the dealer once already. They spent a day just to figure out how to troubleshoot the issue. I offered a few suggestions like removing the tank, put a meter on the sending unit and fill the tank up with water using 1 gallon jugs and read the ohms. If that matches what the engineers in MI say, then the sending unit is good, and it’s either the interface with the gauge or the gauge itself. They looked at me like I was mad. I have trouble shot very complex systems before, so it’s not like I am some kind of idiot. The goes-in and the goes-out does not match so you have to mimic that.

My next suggestions were to replace the sending unit and the gauge. I guess Ford will not reimburse the dealership if a part id replaced under warranty and when it gets back to Ford in MI, they find out it’s a good part.

The checked the ohms of the sending unit (180 is full scale) and that was ok. The next drained the tank and tested it again. Said it was fine. Put 2 gallons of fuel in, and then proceeded to take 26.0 gallons at the chevron station 1500ft away from the dealership. Though that was odd that the dealership states I have a 26.0 gallon tank (verified somehow by Ford in MI), but it took 28 gallons of fuel from being completely empty.

So, I get the truck back last week (first change to bring in since I bought it), and after 150 miles, it doing the same thing. So the problem was not corrected.

If anyone on here has any idea of what the issue is or what I can do, please advise.

I figure that after spending 50k on a vehicle, the fuel gauge should indicate properly.

 

I've actually never seen a fuel gauge track exactly on any vehicle. For example, they might go down from F to 3/4 much slower (or faster) than from 3/4 to 1/2.

I believe that is a function of the shape of the tank.

On this truck, we also have gallons used information which one would expect to be extremely accurate given that these things are fuel injected. Except that bugger is not accurate either as I've commented on before. Mine is off by about 2 gal when I reach about 30 gal used (indicates less gallons used than is actually used).

So now you got two inaccurate things and trying to correlate them will only lead to despair.

So the solution is to ignore one and the one I choose to ignore is the gauge. I can honestly say I never look at it. I go by gallons used and add 2 gallons and then I know where I'm at.

I feel you, though. Not only is this a 50K truck but this is the 21st century.

Apparently in the 1960s with less computing power than is in my microwave oven, we had the technology to figure out stuff like this accurately enough to land a machine on the moon.

I'd be happy if the gal used and mpg could be made accurate. They could then ditch the gauge altogether and put an egt gauge in that spot.

 

I refuel when I get the warning light and it never takes as much to fill it as I expect. I think there are precautions built into it to avoid a completely dry tank, a type of idiot-proofing. Calculated reservoir, almost. My '06 was the same way, could be Ford's been safeguarding their diesel engines for a while now.

ETA - found this in the manual:

 

I absolutely agree with AlexWV's comments. My gauge behaves very similar to what you are describing. I just use the "Gallons Used" counter and ignore the gauge.

To make you feel better, in small airplanes the FAA only requires the fuel gauges to be accurate at 1/2 full level. A lot who fly ignore the gauges and use a burn per hour calculation. On my plane, I use a fuel totalizer that measures the fuel going into the fuel injectors.

 

I refuel when the gauge is at 1/4 tank remaining.
I can't stand to let it get much less.

I received the warning light once and the MTE reported 26.
Even with the 26 MTE, I've always put in less than 21 gal.
Other than that, I ignore the digital MTE screen.

 

I filled up today on the way home.

The truck had warned of low fuel when MTE had reached 60 miles. The gauge was somewhat below 1/8 when the warning came.

By the time I got where I was going to fill up, the MTE had sat on 0 for about 20 miles. The needle of the gauge was close to the bottom but not pinned on the bottom I don't think. Some of the needle was still on top of the E hash mark but it wasn't centered on it.

I planned it this way today because I wanted to see what would happen if MTE hit 0. I was half expecting the truck to throw a hissy fit and put the thing in limp mode or something but it didn't do anything; just arrived on 0 and stayed there.

Gallons used said 34.0 gal.

I put in 35.582 gal which means I still had 2 gallons left.

I made 707.2 miles on that tank.

At no time was I worried because like I said in the post above, I go by the gallons used. Had I been going by the gauge, or even worse by MTE, I probably would have been freaking out at some point.

I'm actually kind of surprised the dealer did all the diagnosing that they did for jrwendell. I doubt there is anything wrong with his truck. At last it is no more wrong than all of them.

 

Back in the day when we had analog clocks, when the hand pointed up, we knew we were on time. Now-a-days, with digital clocks, we know to the tenth of a second exactly how late we are. That's what technology does for us. I just ordered an XLT, thinking I wouldn't have all of the "hi tech" stuff, but now on further perusal I find that I am wrong. I hope I will be able to handle the added stress.