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38 Gal tank experiences....

Discussion in '2.5 Gen Tundras (2014-2021)' started by KeithM, Mar 19, 2018.

  1. Mar 19, 2018 at 7:37 PM
    #1
    KeithM

    KeithM [OP] New Member

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    I've been playing around with my '17 Tundra with the 38 gal tank. Has about 10k miles on it. When I fill up, I get 416 miles to empty per the display. I do almost predominantly local driving, short trips, probably 20-30 miles on most days.

    416 / 13 mpg (worst mpg) = 32 gallons. My mpg sits at 12.9 almost consistently.

    I ran my truck to 0, low fuel warning, and then drove it about another 35 miles. I've driven it further after that warning, but I'm much too chicken to go much beyond that.

    Parked my truck on a near freezing night in my driveway which is on a decent slope down. The front of the truck was lower than the rear.

    Next day, I went to start 'er up, and while it started, it ran super rough, and then stalled. It has never done that before. Uh-oh, gonna be late for work.

    Coasted down to the flat part of my driveway, started back up immediately. Drove it carefully to the gas station two miles away, filled 'er up and it took 31 gallons.

    It seems the usable portion of the tank is really only 31-32 gallons.

    Does this match everyone else's experience?

    Is the pump and/or fuel line connection off the bottom rear of the tank?

    Thanks!
    Keith
     
  2. Mar 19, 2018 at 7:44 PM
    #2
    Y0TA PR0

    Y0TA PR0 Dirt biking & fishing

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    Welcome!
     
  3. Mar 19, 2018 at 7:49 PM
    #3
    ninjajay

    ninjajay Posting from the toilet

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    Must be the angle you were parked at. When my gas light comes on and I have less than 25 miles on the range meter, my fillups are around 31 gallons.
     
    Okimar likes this.
  4. Mar 19, 2018 at 8:01 PM
    #4
    831Tun

    831Tun heartless Bastrd

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    Welcome Keith. You don't wanna run it low on fuel. The fuel helps keep the pump cool if I recall correctly.
     
  5. Mar 19, 2018 at 8:06 PM
    #5
    Metro14536

    Metro14536 New Member

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  6. Mar 19, 2018 at 8:09 PM
    #6
    AndyCBR

    AndyCBR New Member

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    I've read this on several forums and posts but is there any real evidence of this from the mothership to back this up?

    Inquiring minds want to know.
     
  7. Mar 19, 2018 at 8:11 PM
    #7
    BuckWallace

    BuckWallace Ball don't lie.

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    I know this 38 gallon tank has been discussed before, but I wonder if anyone has any actual documented evidence of the usable portion of the fuel tank. Toyota advertising a 38 gallon tank that stalls with 7 gallons remaining (as you said in your experience) seems like a lawsuit waiting to happen. If the fuel pump really is in danger if you run it low on fuel, is there really a 38 gallon tank?

    If I can't use 32+ gallons of fuel in my tank without damaging the fuel pump, I'd say it's BS when Toyota advertises a 38 gallon tank.
     
    Last edited: Mar 19, 2018
  8. Mar 19, 2018 at 8:16 PM
    #8
    831Tun

    831Tun heartless Bastrd

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    Nope, no evidence just repeating what I've rad too.
     
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  9. Mar 19, 2018 at 8:17 PM
    #9
    BuckWallace

    BuckWallace Ball don't lie.

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    I'd think that Toyota will never say the fuel pump is in danger if you use "too much" fuel in the tank. Otherwise they'd be basically admitting that their advertised 38 gallon tank is a half-truth. It reminds me of the case a while back with Apple where it got in trouble advertising a certain hard drive size in its iPhones when only a certain fraction was actually usable.
     
    TTund16 likes this.
  10. Mar 19, 2018 at 8:31 PM
    #10
    SNO BUS

    SNO BUS Professional Moneywaster

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    I think we ran it down to the fuel light, and when we filled up, it was around 28 gallons.
     
  11. Mar 19, 2018 at 8:44 PM
    #11
    KeithM

    KeithM [OP] New Member

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    I don't know the angle of the slope, rise over run, but it's not that steep.

    But surely (7) gallons remaining should be enough to start it up and keep it running?

    I guess if the tank is dimensionally large enough, and the fuel exits from the bottom rear of the tank, that the remaining gas (about 18% of the tank) could be so far forward (when on a slope) as to not reach the fuel line connection at all.

    It sure seems running it below the low fuel warning light is a bad idea!
     
    Artemis1217 likes this.
  12. Mar 19, 2018 at 8:47 PM
    #12
    Big J

    Big J New Member

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    When my light comes on I have around 25-30 miles left per the computer and filling up right then it takes about 28 gallons for me.
     
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  13. Mar 19, 2018 at 8:48 PM
    #13
    Baja Mike

    Baja Mike Baja Aficionado

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    The 38 gallon tank is really a 28 gallon tank. The last 10 is really a reserve to keep the fuel pump submerged. As you've found out running it that low on fuel and parking it at an angle doesn't help. So don't do that any more. :)
     
  14. Mar 19, 2018 at 8:49 PM
    #14
    Big J

    Big J New Member

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    :amen: Not worth burning up a fuel pump over it.
     
    Last edited: Jan 29, 2023
    ATV25 likes this.
  15. Mar 19, 2018 at 9:01 PM
    #15
    SNO BUS

    SNO BUS Professional Moneywaster

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    Hmmm.. I think I'm gonna put that in my signature :D
     
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  16. Mar 19, 2018 at 9:06 PM
    #16
    Steve6

    Steve6 New Member

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    So is the smaller 26? gallon tank really an 18 gallon tank? Am I the only one that thinks that having almost 1/3 of the advertised tank capacity as un-useable fuel is completely retarded?
     
  17. Mar 19, 2018 at 9:08 PM
    #17
    pvdubber

    pvdubber New Member

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    Welcome, and I wonder what the useable portion of the non-38 gallon tank is.
     
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  18. Mar 19, 2018 at 9:09 PM
    #18
    KeithM

    KeithM [OP] New Member

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    Obviously I don't plan to do this repeatedly, but it does help knowing exactly where "true empty" is at.

    My previous RAV4 had a 15.9 gallon tank. I think my largest fill-up was right around 14.5 gallons.....which I define as being "on fumes." But essentially the entire tank was usable.

    The owner's manual says that the low fuel warning light comes on at 5.7 gallons remaining, which is exactly 15% on the 38 gallons. My experience says that maybe it comes on a little earlier than that. But more importantly, you risk not being able to restart it depending on how you're parked. That's NOT in the manual.

    There's also the whole truth in advertising bit too as BuckWallace mentioned up above......

    My friend with a prius (that joke aside) said that his entire tank is about 11 gallons. Imagine if HIS tank become unusable with 7 gallons remaining!
     
    Ranger2005 and htw_hawaii like this.
  19. Mar 19, 2018 at 9:12 PM
    #19
    SNO BUS

    SNO BUS Professional Moneywaster

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    On another car advertised to have a 27 gallon fuel rank, after driving a few miles past the 0 mile range mark, we were able to fill it up to around 26 gallons. Kind of obnoxious that Toyota would advertise 38 gallons but when driven down past fuel light you can only fill up about 31...
     
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  20. Mar 19, 2018 at 9:16 PM
    #20
    KeithM

    KeithM [OP] New Member

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    Yeah my previous vehicles including a RAV4 behaved just like this, the majority of the quoted size was, well, usable.

    More importantly though, is that it at least on my slope, that the truck refused to stay running despite having (7) gallons remaining in the tank!

    Having a "reserve" amount of gas is only useful if you can actually, well, use it!!
     
  21. Mar 19, 2018 at 9:55 PM
    #21
    KeithM

    KeithM [OP] New Member

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    FWIW, I've found that aviation has this concept of "unusable fuel."

    https://en.wikipedia.org/wiki/Usable_fuel

    Essentially when you buy a plane, they quote both the the usable fuel, and unusable fuel capacity.

    Here's an example:

    http://sportysnetwork.com/sportysacademy/wp-content/blogs.dir/3/files/2015/05/C172M-PIM-Opt.pdf

    Search that PDF for "unusable"

    The two interesting parts of what I was able to dig up was:
    • Due to the geometry of the fuel tank some fuel is not usable: "[Unusable fuel is] fuel that cannot be fed into the engine(s): fuel under the pump-intake, fuel behind ribs of a tank, fuel in lines between the tanks and the engines etc."
    • That the actual usable fuel depends on the angle of the aircraft. (ok, ok, the truck)
    So maybe the 38 gallon should be written as 38 gallon/32 usable.

    Has anyone ever filled up more than 32 gallons at a time?
     
  22. Mar 20, 2018 at 5:15 AM
    #22
    JeremyGSU

    JeremyGSU New Member

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    I consistently run my 38 gallon tank down to "0" on each fill up. This typically gets me 30-31.5 gallons back in the tank. I had an '11 Tundra prior with the 26 gallon tank and would only get 20-22 in when I ran it to "0".

    Lots of threads on this. Yes, it sucks that it isn't a true "38" gallon tank but still much better than the 20 gallon.

    https://www.tundras.com/threads/2016-tundra-w-38-gallon-gas-tank-question.3531/

    https://www.tundras.com/threads/38-gallon-fuel-tank.16009/

    https://www.tundras.com/threads/2016-tundra-w-38-gallon-gas-tank-question.3531/
     
  23. Mar 20, 2018 at 5:29 AM
    #23
    Netmonkey

    Netmonkey Don't be a Dumbass

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    I always manually calculate my mileage and fuel usage at every fill up. This lets me know how far I can get on a tank regardless of what the "distance to empty" display reads. When my low fuel light comes on, I have 8 gallons left. For the worst case, this can get me another 100 miles. However, I usually only drive another 30-50 miles. The most fuel I have ever put in the tank on a single fill up is 35 gallons.
     
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  24. Mar 20, 2018 at 5:33 AM
    #24
    15whtrd

    15whtrd Mr. Blonde

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    If it had one of those racing fuel pump pickups with the filter mat that lays in the bottom of the tank, you could get every drop.
     
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  25. Mar 20, 2018 at 5:40 AM
    #25
    Upgrayedd

    Upgrayedd Toyotaholic

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    Ran my 26 gallon tank down to 10 miles on the display and it only took about 20.5 to fill up.
     
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  26. Mar 20, 2018 at 6:21 AM
    #26
    Boerseun

    Boerseun MGM XP-Series

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    I think it is basic physics. The 38-gal fuel tank is about 6 feet long. To compare it with a small tank that is real short and the last little bit of gas has nowhere else to go than to be close to the pump, is not a logical comparison. With the length of the tank it is just reasonable to accept that there will be times when you go downhill for instance that the front end of the tank will be lower than the rear, and there will be a significant amount of fuel in that front part of the tank. Other than mounting the tank on a gyroscope, there is not much you can do about it. I would say just accept that you will have on average 32 gallons 'usable', and live with it. It is still better than having a 26-gal tank with 20 usable, or a 9-gal tank with 8-gal usable. Just my opinion.
     
  27. Mar 20, 2018 at 6:32 AM
    #27
    Steve6

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    What you're saying is true; however, my other vehicle (93 Bronco) has a 32 gallon tank and I've put over 30 gallons in it during refuel. I accept that there will always be some un useable fuel but I think that six to eight gallons is excessive for a 38 gallon tank. Now I'm really glad that I got the 38 gallon tank; at least I have 30 useable gallons.
     
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  28. Mar 20, 2018 at 6:59 AM
    #28
    pinellasjoe

    pinellasjoe New Member

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    Almost 10k miles on the Tundra and same results for me. Usually fill up is right at 31 gallons.
     
  29. Mar 20, 2018 at 7:03 AM
    #29
    zcarpenter92

    zcarpenter92 Yotas and Yellow Jackets

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    Not sure why this is such a common topic of discussion...big whoop, it’s designed to only let you use 32 gallons.
     
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  30. Mar 20, 2018 at 7:42 AM
    #30
    KeithM

    KeithM [OP] New Member

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    Thanks for your message. During much obsession last night, as is typical for me, I discovered that the fuel pump assembly that inserts in the gas tank has an inlet with filter sock that faces one particular direction. This assembly is also offset from the center --- not smack dab in the middle like many other vehicles. Dunno if there are any mechanics here that have seen this firsthand, but depending on the specific location and direction of that inlet, if the gas isn't "within reach", it's not within reach.

    There are obviously other designs, from other manufacturers, that allow for better efficiency and performance.

    EDIT: I do wonder if there are racing fuel pump pickups for the Tundras. :)
     

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