Always one gallon more
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Elder User
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Always one gallon more
For the last decade or so, if I'm not towing or on a long highway trip, I have always filled up my trucks when they get down to 1/2 tank. I have noticed on the 6.7 that it always takes about one gallon more than the computer claims it has used. Yesterday, it said I had used 17.1 gallons. I filled her till it clicked off and as usual the pump says 18.1 gallons. Isn't that about a 5.5% error? That seems huge considering how advanced the computers are. Locally I only use one of two stations that are the same brand and company with the same pumps. Has anyone else noticed this or could it be just my truck? I hope the pumps aren't ripping me off for that gallon but I do also use them for gas in the van and they seem correct.
Senior User
Joined: Oct 2015
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I have a theory about that. I have displayed on my torque pro app % fuel remaining. That should match my fuel gauge, but it doesn't... at least not until it starts getting closer to Empty. for instance, when the gauge shows 3/4 exactly, my % is quite a bit lower, like almost 5%. My theory is that this gives the consumer the false sense that they are getting better mileage than they really are. I've always felt vehicles have done this... not just Ford, any I have ever driven. My theory is that it's a game the manufacturers play. Not a fun game, but those are my thoughts.
And just for grins, there are other gauges that don't match... for instance MPH.
And just for grins, there are other gauges that don't match... for instance MPH.
Laughing Gas
Joined: Apr 2003
Posts: 1,188
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From: Olympic Peninsula
Interesting, both my 2012 F250 and 2015 F350 will almost always take less fuel than the display says I burned. Typically this is at least a gallon less than it states. I am a fill it up prior to getting below a quarter thank, so it doesn't bother me.
I just wish my F350 was as magical on fuel mileage as my F250 was, but don't complain because I like the power and engine brake in the 2015 better.
I just wish my F350 was as magical on fuel mileage as my F250 was, but don't complain because I like the power and engine brake in the 2015 better.
Senior User
Joined: Nov 2011
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From: Fox Lake, WI
For the last decade or so.....snip....I have noticed on the 6.7 that it always takes about one gallon more than the computer claims it has used. Yesterday, it said I had used 17.1 gallons. I filled her till it clicked off and as usual the pump says 18.1 gallons. ....snip.....
My experience is similar to yours- my fill ups always take about 0.9 - just shy of a gallon, more than the display indicates.
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Elder User
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The computers in my 1999 and 2004 always claimed better mileage than I got. I think it could be possible they are configured to tell us the mileage is better than it is. I don't think I have the fuel gauge turned on on my Torque Pro, but I will now.
Mountain Pass
Joined: Dec 2015
Posts: 128
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From: N. IL
Interesting, both my 2012 F250 and 2015 F350 will almost always take less fuel than the display says I burned. Typically this is at least a gallon less than it states. I am a fill it up prior to getting below a quarter thank, so it doesn't bother me.
I just wish my F350 was as magical on fuel mileage as my F250 was, but don't complain because I like the power and engine brake in the 2015 better.
I just wish my F350 was as magical on fuel mileage as my F250 was, but don't complain because I like the power and engine brake in the 2015 better.
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Elder User
Joined: Mar 2002
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From: Central BC, Canada EHH
My trucks have been very accurate, with the stock tank so far what the pump meter totals is within 1L of the trip meter. Even with the Titan tanks adding +200L's of fuel it would be off less than 1L. Might be some shoddy pump calibration....
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More Turbo
Joined: Dec 2011
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It has nothing to do with the fuel tank. The computer reports what it believes went thru the injectors. The fuel is not weighed or measured. Injectors aren't perfect and fuel pressure will have some variation. It is just a best guess.
Fleet Mechanic
Joined: Jun 2011
Posts: 1,865
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From: Annandale, VA
My 2011 F-350 as very accurate when hand calculated vs the computer. My 2014 was never even close, often used a gallon or more than what the computer says.
The Ram also over predicts fuel economy. Sometimes you get a good one and sometimes the actual values just barely fit in the 1 standard deviation.
Hotshot
Joined: Apr 2013
Posts: 10,121
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From: NH
But don't forget about "miles to empty" calculation. That indeed relies upon what remains in the tank contrasted against a running average fuel economy. The OP's question regarded why the computer may have said, for example, 25 gallons were used but 26 gallons were needed to fill the tank.
The answer to that question, most likely, is based upon how much fuel is stored in the filler neck. If you have a 26 gallon tank, for example, the computer can only read the tank is "full" with a capacity of 26 gallons. However, if you are like me, after the tank clicks off, I let the foam settle, and then slowly add more fuel until it clicks off again. There is actually a little bit of room in the tank above the fuel level float, and a fair amount of room in the filler nozzle. I would say you could probably fit an extra gallon in this area.
Senior User
Joined: Jul 2012
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Mine us usually within .3 gallons. A lot of it depends on how you fill up. I fill it up on the slowest speed, then round up to the nearest quarter after it shuts off. Except at the truck islands, do not try to top it off, as the fuel chased me away.
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Elder User
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Well, this is mostly right. Fuel "usage" absolutely relies upon what went through the injectors.
But don't forget about "miles to empty" calculation. That indeed relies upon what remains in the tank contrasted against a running average fuel economy. The OP's question regarded why the computer may have said, for example, 25 gallons were used but 26 gallons were needed to fill the tank.
The answer to that question, most likely, is based upon how much fuel is stored in the filler neck. If you have a 26 gallon tank, for example, the computer can only read the tank is "full" with a capacity of 26 gallons. However, if you are like me, after the tank clicks off, I let the foam settle, and then slowly add more fuel until it clicks off again. There is actually a little bit of room in the tank above the fuel level float, and a fair amount of room in the filler nozzle. I would say you could probably fit an extra gallon in this area.
But don't forget about "miles to empty" calculation. That indeed relies upon what remains in the tank contrasted against a running average fuel economy. The OP's question regarded why the computer may have said, for example, 25 gallons were used but 26 gallons were needed to fill the tank.
The answer to that question, most likely, is based upon how much fuel is stored in the filler neck. If you have a 26 gallon tank, for example, the computer can only read the tank is "full" with a capacity of 26 gallons. However, if you are like me, after the tank clicks off, I let the foam settle, and then slowly add more fuel until it clicks off again. There is actually a little bit of room in the tank above the fuel level float, and a fair amount of room in the filler nozzle. I would say you could probably fit an extra gallon in this area.