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Fuel tank size vs. fuel gauge

9694 Views 38 Replies 29 Participants Last post by  ram360
Every time I run my 2013 2500 down to 1/8 of a tank and then when I fill up it only takes 22 gallons? I thought our trucks had 31 gallons? So that last 1/8 th tank is 9 gallons? Something is off?
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My dad says the same thing about his 2013 3500. I believe the tank size is 32 gallons. They give a big buffer before you run out. He wants a bigger tank in his.
I see the same thing on my 2013, I have yet to put more than 28 gallons, and the gauge was on E when I did that. Didn't want to take it that low, but had to wait till the next day to get the $.10 off a gallon. But after seeing it still had 3 gallons left, no harm no foul
Lol. Next time run down to a 1/32 of a tank, see what happens.




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Almost no fuel gauges are linier anymore. They are all heavily biased toward full.

For my 2010 it goes something like this when on the highway empty.

full > 3/4 = 200 miles
3/4 to 1/2 = 150 miles
1/2 to 1/4 = 150 miles
1/4 to E = 50-60 miles

When hovering around E it will usually take about 30 gallons (34 gallon tank).
I do believe its a 28 gallon tank, although the user guide says 52 gallon rear or 22 gallon mid ship is options...dont know any of the 6.7 that have that capacity unless your talking chassis cab 4500 and 5500...I dunno.
They must all be like that. My '97 was the same when it was new. I dropped the tank, took the sender & float out, bent the float arm down until it almost touched the bottom of the tank, and problem solved. When the yellow low fuel light comes on, I have about 50 miles left, and when it is pegged on "E", I have about a gallon left. The way it was to start with, the float arm bottomed out on travel, and hung about four inches above the bottom of the tank.
I have a 2014 long box and my fuel light will come on at 1/8 of a tank and will consistently show 100km to empty and will take 102 - 105 liters every time. I just like that it's constant.


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My 2012 had a 32 gallon and would take 28 to 29 gallons constantly, but I have heard rumors because of def and better fuel consumption they put a 28 in the SRW and 31 gallon in DRW. I dunno, just what I hear and seems legit at 28 gallons from my fill ups
According to what my dealer said and I am giving just my experience from my limited testing the 13 comes with "extra 5 gallons" on my window sticker and that means it is a reserve. If you look at your gauge there is a thin red mark just before the last fill line and that is where the reserve starts. I have taken it to that line and I filled up to about 26 gallons. The manual says SB have 31 and LB 32 gallons.
Now I have only done with my truck and using that thin red line and it leads me to believe what the dealer said the reserve is there and stays full until you reach empty then give you the extra to find a place, if you don't reach the reserve you can only get 26 or so gallons
I hole this helps and if there is a different reason than what I was told I am interested as well.

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what page of your manual? page 165 states some BS numbers
what page of your manual? page 165 states some BS numbers
Page 141 of diesel manual
Snapped a pic

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I had to download 2 additional manuals specific for the diesel. And that is where the info is.

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I can't believe there's actually a debate about this. All fuel tanks have a reserve capacity below "E". Has been that way for many many years.

If they didn't, (1) you'd be stuck wherever you happened to be when the light came on and (2) you'd have to reprime your fuel pump (or buy a new one) every time you ran out of gas. 4-5 gallons is typical but it depends on the mileage of the vehicle in question. My Tundra had a 9 gallon reserve below "E" because towing they get abysmal mileage and Toyota wanted to ensure folks wouldn't get stranded. My motorcycle on the other hand has a 0.9 gallon reserve.


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I run it all the way down till the range displays low fuel. And the needle is on E. I was filling up at the first red line and it was around 24 gallons. Now after driving 15-30 miles in 'E' its 28 to 29 gallons. I aim to fill up around 550 miles each tank. My commute is consistent. 2013 short bed for reference.

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I was very confused about the seemingly small tank after having my 2011. Thanks for clearing it up for me.

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Thanks joe, my damn truck just came with a generic manual not diesel....talk with the dealer about this.
According to what my dealer said and I am giving just my experience from my limited testing the 13 comes with "extra 5 gallons" on my window sticker and that means it is a reserve. If you look at your gauge there is a thin red mark just before the last fill line and that is where the reserve starts. I have taken it to that line and I filled up to about 26 gallons. The manual says SB have 31 and LB 32 gallons.
Now I have only done with my truck and using that thin red line and it leads me to believe what the dealer said the reserve is there and stays full until you reach empty then give you the extra to find a place, if you don't reach the reserve you can only get 26 or so gallons
I hole this helps and if there is a different reason than what I was told I am interested as well.

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I think that references the 5g of diesel that factory puts in it upon delivery.
My dad says the same thing about his 2013 3500. I believe the tank size is 32 gallons. They give a big buffer before you run out. He wants a bigger tank in his.
Mine as well, thought it had 52 gal tank and I was pumped. Put 22 gallons in on my first fill-up and was thoroughly confused. Pics went to dodge's website and entered my VIN and got my trucks build sheet and it says 32 gal tank... So which is it? 22/32/52?!?! I would love to have a 52 installed in my Dually
Some bad news for you, max tank size from factory is 32 gallons....

Mine as well, thought it had 52 gal tank and I was pumped. Put 22 gallons in on my first fill-up and was thoroughly confused. Pics went to dodge's website and entered my VIN and got my trucks build sheet and it says 32 gal tank... So which is it? 22/32/52?!?! I would love to have a 52 installed in my Dually
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