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Fuel tank: gauge indicates full, but it isn't

Discussion in '1st Gen Tundras (2000-2006)' started by yonsay77, Dec 4, 2020.

  1. Dec 4, 2020 at 5:04 PM
    #1
    yonsay77

    yonsay77 [OP] New Member

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    2005 Double Cab 2WD 4.7L V8

    Hey Fellow First Gen Owners,

    I've some research and called every local shop nearby who have now blocked my number. Haha! My tank is indicating it's full, but it can't be full based on the 25.6 gallon capacity. I'd really appreciate any insight you can provide. I'm trying to avoid dropping the tank, but it sounds like that may have to be done.

    Here are the numbers:
    With 1/4 tank used = can only fill up 3.7 gallons until shutoff
    With 1/2 tank used = it takes about 7-7.5 gallons until shutoff
    With 3/4 tank used = takes about 11 gallons shutoff

    When I start the truck, it says full. With a 25.6 gallon tank (even taking into account a few gallons for reserve), it should be taking more gas than this. Any ideas?

    Additional info:
    - NO check engine or code errors on
    - Just passed SMOG
    - NO leaks or condensation on the gas tank underneath
    - NO kinked hoses

    Possible problems:
    1. Bad sending unit or gauge
    2. Clog in hoses
    3. Displacement of air causing a malfunction
     
  2. Dec 4, 2020 at 5:10 PM
    #2
    SouthPaw

    SouthPaw The headlight guy

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    A simple test is to smack the bottom of the fuel tank and see if the needle changes.
     
    Stuck in the '00s likes this.
  3. Dec 4, 2020 at 7:23 PM
    #3
    yonsay77

    yonsay77 [OP] New Member

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    I'll give that a shot tomorrow. I read about that, but I wasn't it taking it seriously.
     
  4. Dec 4, 2020 at 8:01 PM
    #4
    assassin10000

    assassin10000 New Member

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    Possibly reading emptier than it is. Could be the sender or gauge. Ever try and run it til the low gas light comes on?
     
    Punk1974 likes this.
  5. Dec 4, 2020 at 8:44 PM
    #5
    yonsay77

    yonsay77 [OP] New Member

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    Thanks, Assassin. I'm running this tank out, so I know where it falls at the quarter measurements. Yeah, the sender or gauge will require a lot of labor, so I'm preparing for the worst.
     
  6. Dec 5, 2020 at 3:00 AM
    #6
    Festerw

    Festerw New Member

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    It sounds off but not too far different from mine. If I let it go to empty it'll take about 17 gallons, when the light comes on about 20.

    The most I've ever put in was 22.
     
  7. Dec 5, 2020 at 3:28 AM
    #7
    Wallygator

    Wallygator Well Zippedy Da Do!

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    Well good luck in figuring this out but IMO I would not tear into the tank, on a 15 year old vehicle, and replace the sender just to get the fuel gauge more accurate. I mean just make a mental note on your mileage and fill up when you get to that mileage. For example if a full tank nets you 300 miles, fill up when you get to 250. Use A or B trip meter. YMMV.
     
    Tundra2 and des2mtn like this.
  8. Dec 5, 2020 at 4:56 PM
    #8
    yonsay77

    yonsay77 [OP] New Member

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    I appreciate all of the replies. I agree it's not worth dropping the tank. I'm at about 3/8 of tank left, and I've only gotten 130 miles on this trip. More than half of those are freeway miles, so it's very odd. I'm going to run it to near empty a few times and see how the system responds before paying anything to have a shop look at it. I'm just glad I don't have error or check engine lights on. I've already replaced the air filter, changed the oil, ran a fuel system cleaner through it. On the bright side, if it takes less gas, I'll be spending less each time I go to fill up. I don't drive much, so it's more of a "What the heck's going on?" than a huge concern.
     
  9. Dec 5, 2020 at 7:40 PM
    #9
    Stuck in the '00s

    Stuck in the '00s Experienced member

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    I'd lean toward the fuel sending unit as your gauge seems to function.
    I'd also lean toward the float arm being incorrectly adjusted OR the unit was replaced with the wrong part.
    See where the gauge reads when it's empty and advise.
     
  10. Dec 6, 2020 at 8:04 PM
    #10
    yonsay77

    yonsay77 [OP] New Member

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    Once again, thank you fellow forum and first gen supporters! Great suggestions and possible parts to look at. I think the fuel system cleaner is helping, but it may need another treatment just to make sure everything gets a good refresh. The old owner just did oil changes and then I think it sat for a while while he tried to sell it.
     
    Stuck in the '00s likes this.
  11. Dec 7, 2020 at 9:51 AM
    #11
    rock climber

    rock climber New Member

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    Mine too. I was really annoyed by this and so I made sure to run it down a few times to where I got 24 gallons in, then fried my fuel pump. The remaining 6 gallons cool the fuel pump.
     
  12. Dec 7, 2020 at 10:05 AM
    #12
    Festerw

    Festerw New Member

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    I drive by my preferred gas station each way to work, just took a little time to figure out I didn't NEED to stop when it got close to empty. Now I just go until the light comes on and don't worry about it.
     
  13. Dec 7, 2020 at 5:32 PM
    #13
    yonsay77

    yonsay77 [OP] New Member

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    Great advice from everyone. Good lookin out, Rock Climber! I definitely don't want to burn out the fuel pump. Once it gets to "E" and the light comes on, I'll head to the gas station and see how much it takes. I beginning to think it really just sat for over a month, so it'll take a few tank cycles to get the sending unit and other parts moving freely again. At 3/4 of the a tank used, I was able to go 40 more miles with the same type of driving on this tank than the last. Festerw, you're right about the abundance of gas stations. First gens are awesome, so it's worth the extra work and time to get to know how our trucks operate.
     
  14. Nov 23, 2021 at 2:15 PM
    #14
    Santa Cruz Tundra

    Santa Cruz Tundra New Member

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    Hi. I’ve been reading the posts for years and decided to chime in on this one. I would suggest NOT running the tank to empty. I’ve always been missing 6 gallons and assumed it was the hidden reserve. Historically it’s never take more than 21 gallons.

    That means when the light comes on I should have roughly six gallons. I more often than not run the tank until the light comes on and being the anal retentive control freak that I am I didn’t like Toyota taking my six gallons. I know it’s to cool the pump but I decided I was going to track how many miles from when the light comes on I can go. I average 15MPG so figured I could get 75 miles before empty.

    I loaded my gas in the truck and off I went. The first couple of tries I could not go past 40 miles once the light came on because of where I was geographically and not wanting to chance it. Then it came on the 3rd time and I was in a good location to be able to throw a gallon in and get to a gas station. I reset my average MPG and I ended up getting 47 miles before I ran out. I wondered where the rest of my 26 gallons is?

    if was a dumb freshman move deciding to run empty. After putting the gallon in and filling back up I did my usual driving. My gauge went down to a little over a 1/4 tank. Next thing I knew I ran out of gas. I’ve tested the fuel sending unit and banged the tank while filling. I put a mechanics stethoscope on the tank as well. Don’t know why I did that except to use the tool and feel smart. It would appear as though I’ve fried my fuel pump. The point of my post is I would suggest not running it to empty and except Toyota’s engineering. In the grand scheme of things they make the best car in the world so it’s a minor trade off. This my second tundra. My 03 made it to 300,000 miles. I have a 97 4running that’s at 492,000. I love that truck. Gonna take her past a half a million and leave her to my son to take past a million when I’m gone. I’m rambling. That’s one of the reasons I don’t write in these listing. I ramble.
    Thanks everyone. Hope this saves someone.
     
    lonedrake likes this.
  15. Nov 24, 2021 at 8:42 AM
    #15
    yonsay77

    yonsay77 [OP] New Member

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    Santa Cruz,
    I appreciate the response and insight. I don't drive much, so I just fill it up when it gets to a 1/4 tank and don't worry about it even though it seems off. The new Tundras look nice, but I'm not sure about dropping $65K for what I want. Dreams!
     
  16. Nov 24, 2021 at 8:51 AM
    #16
    Schcoman

    Schcoman From behind the Redwood Curtain

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    I had an old Ford Ranger that had a similar problem, read full until the last minute and would drop to empty. Since I had a good idea what my milage was, I would fill and reset the trip ODO and just watch my miles knowing when to fill up. Easier than dropping the tank and trying to fix the sender. I do NOT like running the tank low on an older vehicle. Lots of gnarly stuff in that last gallon lurking at the bottom of the tank.
     
  17. Nov 24, 2021 at 9:07 AM
    #17
    Punk1974

    Punk1974 former 2000 owner looking for a fg tunny project

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  18. Nov 25, 2021 at 7:12 AM
    #18
    bmf4069

    bmf4069 Yup, that's car parts in a dishwasher

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  19. Nov 25, 2021 at 11:25 AM
    #19
    Sirfive

    Sirfive Master Procrastinator

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    If i ever do the tundras fuel pump, im gonna tweak the bend in the float to say empty early. Never a good idea to run a tank low.
     

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