Weird Fuel Tank Question

[ksneubec]

I wasn't even sure where to post this, so I put it in the general forum.

I am the happy owner of a 3 month old '21 Ram Rebel. I ordered the 33 gallon fuel tank and my dealer tells me it was properly equipped, as does the build out. HOWEVER, I have never been able to put more than 29 gallons of fuel into it. I've let it get as low as 8-10 miles left of driving and at most I get those 29 gallons in. I'm thinking (and correct me if I'm off) that I have the 26 gallon tank (standard, right?) and the extra three gallons are a fuel reserve plus whatever fuel is between the tank and the entry point? What are people's thoughts? Any suggestions on how to confirm exactly what size I have?
Any other vehicle I've owned, I've always been able to put in very close to the full amount of fuel when I'm down to less than 10 miles of driving. I had a Raptor previously with a 36 gallon tank and I was putting in 35+ gallons when I was down to 10 miles until empty.

Thanks in advance for any suggestions.

 

[Sascwatch]

These trucks seem to keep some extra fuel in them above the miles to empty range. Most likely to prevent the pump from ever running dry and overheating.

Factory options are 23, 26 and 33 if I remember correctly, so if your getting 29 gallons in I’m sure you have the correct tank.

 

[RAMpressedLimited]

The 8-10 Miles DTE you are seeing are based off of MPG calculation, which, in my opinion, isn't the best judgement. I have been in the automotive industry in various capacities for over 15 years now, from my experience I have never heard of or seen a "reserve" portion in a automotive fuel tank. Also, the amount of fuel from tank to injector rail is negligible.

That being said, if you're putting in 29 gallons, I'd say its a safe bet that you have the 33 gallon tank.

 

[Rlaf75]

I believe tank capacity is measured with an empty tank. When I say empty I'm talking about no fuel pump module and baffles and whatever else may be in there. Literally a hollow tank. Everything they put in the tank displaces that amount of gas you can put in. If you're getting 29 gallons in then you have a 33 gal tank. I have the 26 gal tank and I have never been able to get more than 23 or 24 gals in it and I've run out of gas

 

[Whoa_Ram]

I'm in the same boat. I've gotten down to it showing 20 mile range and when I pump I only put about 20 gallons in my 23 gallon tank. It makes me want to upgrade my tank asap.

 

[ksneubec]

Thanks for all the replies, I appreciate the guidance.

 

[mikeru82]

Every Ram truck I've owned has been like this. Even with the DTE around zero the amount of fuel I could stuff in was 3 to 4 gallons less than the stated tank capacity. The two 4th gens I owned were the same way. Just enjoy your new truck and know that you have the largest tank available. And congrats on your new Rebel!

 

[Buz]

I think as we're stuffing more and more technology into vehicles, the results of running out of gas are more and more dangerous. So perhaps the auto industry does build in a 'buffer' when calculating the DTE?

 

[IvoryHemi]

When the range drops from “10 miles” to “Low” there is about 2 gallons left.

At that point it will pump in ~31 gallons

 

[Richard320]

Sounds right. My truck shows empty with about 4 gallons left in the tank. So does my wife's car.

 

[SkittleRam]

I have been able to fill up to 31 gallons in my 33.

 

[Mountain Whiskey]

Thanks for all the replies, I appreciate the guidance.

Drive until you start sputtering and stall out. Then you can see how much it takes to fill it.

 

[TNRamGuy]

Drive until you start sputtering and stall out. Then you can see how much it takes to fill it.

I believe that this can only happen with 3.92 abominations, 3.21 never run out of fuel

 

[HSKR R/T]

I believe tank capacity is measured with an empty tank. When I say empty I'm talking about no fuel pump module and baffles and whatever else may be in there. Literally a hollow tank. Everything they put in the tank displaces that amount of gas you can put in. If you're getting 29 gallons in then you have a 33 gal tank. I have the 26 gal tank and I have never been able to get more than 23 or 24 gals in it and I've run out of gas

That's not true about the baffles and pump displacing that much fuel. Most 1999 and newer vehicles I have driven/owned always have at least 2 gallons left in the tank when the gauge reads empty and DTE reads zero, or low. My 2000 Dakota I know I can go about 40 miles ones the trip computer reads zero DTE. And I have actually put 21.5 gallons into the 21 gallon tank on that truck at one time

 

[kdoublep]

I got a 26. Get about 23 or 24 in depending how low I go but I haven't gone that low often. I usually fill up at about a qtr tank.

 

[Mountain Whiskey]

I believe that this can only happen with 3.92 abominations, 3.21 never run out of fuel

Yep, better gas milage than a Tesla!

 

[MikeyHo808]

I also have the 33 gallon tank, and have not put in that much on an empty tank. That being said, @$3.59 gallon for 87, and $3.79 for 92 @ Sam’s in Hawaii, I try as much as possible to fill up around a half tank. I also alternate 92 octane every other fill up cuz Sams don’t carry 89. My very first tank fill up with this truck was almost empty, 28 gallons total, that was a painful fill up‍♂, so Im trying not to do that again.

 

[KWKSLVR]

I have always been under the impression that the "reserve" terminology has to do with what is left in the tank after your trip computer says 0 miles left to empty. In the case of my Camry, this appears to be right around 2 gallons, or an extra 50-70 miles worth of fuel. It also has a 17 gallon tank that I routinely put 15 - 16.2 gallons into (I like to live on the edge) so I'm not sure how much space the fuel pump and lines displace .

 

[mikeru82]

I also have the 33 gallon tank, and have not put in that much on an empty tank. That being said, @$3.59 gallon for 87, and $3.79 for 92 @ Sam’s in Hawaii, I try as much as possible to fill up around a half tank. I also alternate 92 octane every other fill up cuz Sams don’t carry 89. My very first tank fill up with this truck was almost empty, 28 gallons total, that was a painful fill up‍♂, so Im trying not to do that again.

Hahaha I've been doing that too. In my mind I know I'm spending the same amount on gas. It's just less painful if it comes out in smaller chunks