How many pips before you get gas

Discussion in 'Gen 3 Prius Fuel Economy' started by Sparkman 3, Apr 11, 2013.

  1. MarcSmith

    MarcSmith Active Member

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    it's not a game, I agree no one want to be stranded...knock wood I've only run out of gas once on a motorcycle since I started driving nearly 30 years ago.

    when you have a 12 gallon tank. in theory @ 1/4 tank you should have 3 gallons left.

    so with 10 pips...2.5 pips should equal 1/4 of a tank so when you have 2-3 pips remaining you should have 3 gallons .

    I ran the tank until I had one pip flashing and I still had 2.5 gallons or nearly 100 miles until dry...or about 1/4 of a tank.

    I'm not the kind of person that wants to fill up when I still have half a tank in the car. whats the point of having a tank that you can go 400+ miles only to fill up after 250.

    even though I am in the burbs the closest reasonably priced fuel is 2 miles away from my normal route, my normal route to work takes me into the "high rent district" and fuel is typically 20-50 cents more expensive. so if I can wait until I can make a trip into the low-rent district, I'm all for it...

    Basically today I learned something important about my car, that on my car and my fuel gauge... 1 pip= 1 gallon of gas... and if I wait until the last pip starts flashing I have a 2.5 gallon "reserve" or about 80 miles until the pucker factor kicks in...which is about the same thing everyone else has stated...

    And thats my reason for "pushing the envelope" so to speak. If I'm going to have a bad experience with the fuel gauge, Id' rather do it in an area that I'm familiar with... as opposed to on the highway in BFE.

    So will I push the envelope until the last pip disappears? no.. but I won't go into panic mode either when I only have 2 pips showing.

    On a side note...since the engine is fuel injected and the OBDII is metering and pumping fuel, one should think that the computer should be able to tell us exactly how much fuel it has used...
     
  2. Munpot42

    Munpot42 Senior Member

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    I think that Toyota put a greater cushion of reserve gas in the Prius because of the necessity of adding 3 gallons to get the car to start instead of one and for the tendency of some folks to try to drive on electric only until that fails. When you have run the traction battery down apparently other bad and expensive things happen. Your average owner won't know that and will be upset when having to foot the bill, so to protect the ignorant an added margin of gasoline seems a safe bet forToyota
     
  3. MarcSmith

    MarcSmith Active Member

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    definitely makes sense for fuel gauges to be more pessimistic... better to show E and have some "reserve"
     
  4. KingToph

    KingToph New Member

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    I just bought a 2012 Prius 2 weeks ago and was wondering why when I got to the blinking PIP on my first fuel-up it did that. I filled up when it estimated I had 5 miles left but it only took 9.6 gallons of gas to fill.
     
  5. Munpot42

    Munpot42 Senior Member

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    Toyota lies to you because they really, really don't want you to run out of gas, you can check my earlier post (about 2 up) for an explanation.
     
  6. fuzzy1

    fuzzy1 Senior Member

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    For an estimate of how much gas was really remaining, read the first post of this thread: [WARNING] Running out of gas (Gen III)

    The real story of what happened is buried deep in the thread, but the first post alone should be sufficient to address your question.
     
  7. fuzzy1

    fuzzy1 Senior Member

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    The Prius reserve cushion isn't noticeably different than those of the last three non-hybrids I had before it, a Ford, a Honda, and a Subaru.

    I intentionally ran my last Ford out of fuel as a test. It went about 120 miles past the low fuel warning light, about the same Bob gets on his 2010 Prius. I never ran the Honda and Subaru fully out, but based on refill quantity at sixty miles past the last warning, estimate that they would do roughly the same.

    That old Subaru was replaced by a new one a couple months ago. The first hint suggests that it has far less reserve cushion than the old one, but I won't put it to a test until warmer weather arrives.

    My first Ford was quite different. It had negative reserve cushion, running out of fuel with the needle still above 'E'.
     
  8. bwilson4web

    bwilson4web BMW i3 and Model 3

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    I've started both Prius with just 1 gallon after running the tank dry. The three gallon limit is just to turn off flash, which professional 'dry-tankers' don't care about anyway.

    Bob Wilson

    How do we turn off the Tapatalk ad?
     
  9. princessprius

    princessprius Junior Member

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    I'm a bit confused.
    I let my car get down to zero+ a couple times by accident, but never ran out of gas.
    I also let it get to one flashing pip and even a beep, numerous times.
    Then I read somewhere on this forum, a couple years ago, that you are not supposed to do that with a Prius because if your gas gets too low it causes a problem with something else (fuel pump I think?) to the extent that you may need to replace it sooner than usual.
    Yet here you guys are, running out of gas on purpose and nobody has mentioned this.
    Am I remembering this wrong, or what?
     
  10. jdk2

    jdk2 Active Member

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    The guys doing that are doing so for distance tests. In normal day to day driving, there's really no good reason to allow the fuel tank to get that low. The fuel pump is in the tank and is cooled by fuel. Why risk damaging the pump or worse while you're sitting on the side of the road waiting for someone to bring you fuel?
     
  11. fuzzy1

    fuzzy1 Senior Member

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    This is one of very many issues where different people have different experiences, different needs, different wants, and different abilities to deal with different challenges. Not surprisingly, this leads to different opinions.

    On this, as with many things, there is no central authority that declares one specific path as the truth that everyone must obey. We have freedom of choice in who to most believe, and how to run our own life and car. And when things don't work out as expected, well, somebody probably warned us that could happen.

    PC has many discussions about running the fuel tank low, and the warnings you remember get repeated in many but not all threads. Most of the potential problems are common to cars in general, not just to Prius.
     
  12. bwilson4web

    bwilson4web BMW i3 and Model 3

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    I was curious and the results:
    • ~40 dry tank events in our 2003 Prius - nothing broke, it continues to run just fine. Part of gasoline quality tests.
    • ~7 dry tank events in our 2010 Prius - nothing broke, it continues to run just fine. Included the E85 testing.
    • full tank E85 in our 2003 Prius - check engine light came on. Some stumbling on freezing temperature, cold-soak morning. Did require a second start attempt but otherwise, it continues to run fine.
    • full tank E85 in our 2010 Prius - check engine light came on. Some stumbling on freezing temperature, cold-soak morning. Did require a second start attempt but otherwise, it continues to run fine.
    • installed 1kW, 12V-to-112VAC, modified sine-wave inverter in our 2003 Prius - we have used it at least once per year, once for over four days, no problems.
    • installed 1.5kW, 12V-to-112VAC, sine-wave inverter in our 2010 Prius - not used for emergencies, yet, but have used it for remote power operation.
    • used a 3-axis accelerometer to measure 'brake pause' - shortly afterwards, Toyota announced a software patch.
    • installed tow receiver on 2003 Prius - have used it to tow both folding trailer, jon boat, and 1,000 lb empty boat trailer
    • installed tow receiver on 2010 Prius - have used it to tow 1,700 lbs of trailer and airplane 600 miles
    • driven 100 mph and measured the MPG in our 2003 Prius
    • driven 100 mph in our 2010 Prius while taking a cell phone clip
    • different sized, 51 psi tires on our 2003 Prius - larger diameter pair on the front gives ~6% overdrive and improves straight-line stability
    • four-wheel tow and camber alignment on our 2003 Prius - minimizes tire effects on handling and maximizes tire life
    • upgraded traction battery in 2003 Prius - when prices were lower, swapped it for better quality modules and buss bars in one professionally balanced
    • hard braking in 2010 with one side on snow-ice and the other on dry pavement to see the traction-control operate
    • hill-hold test with 2010 Prius - works fine
    • air inlet block for 2003 Prius - works fine and is in the car until temperatures reach 70F
    • air inlet block for 2010 Prius - works OK but not that useful in North Alabama temperatures
    • mapping cold-weather temperature modes in 2010 Prius
    From time to time, folks have read about my experiments and posted with their 'hair on fire'. But I am a curious and prefer to address technical questions that my experiments might provide insights.

    So do you have any technical questions?

    Bob Wilson
     
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  13. la9ers

    la9ers Junior Member

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    Yesterday I manage to run out of gas while driving on the highway, luckily there was a gas station a mile away. As i was driving i was not able to accelerate correctly and noticed i was on battery only, the wired part no emergency lights came up. i got to the gas station with only 3 bars left on the battery i knew if i drained the battery out i was screwed. I noticed after filling up 12.1 gal of fuel the ice engine wouldn't start i panic a little but thanks to my note 2 phone I got on PC and saw a post regarding the same issue... i had to power cycle the car for the engine to start. after a few minutes the battery started to charge. I knew what i was doing, i was just testing my limits......

    notification beep came on at 469 miles
    ran out of gas at 596 miles
    system MPG 53.0
     
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  14. Mendel Leisk

    Mendel Leisk Senior Member

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    What's involved in "power cycle"?

    (I happen to know I'll never be running out of gas, unless the tank takes a bullet, but still curious)
     
  15. bwilson4web

    bwilson4web BMW i3 and Model 3

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    When on 'flash', switch to energy flow display. When the arrows go away, you are on traction battery.

    Bob Wilson
     
  16. bennela

    bennela Junior Member

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    Well, the furthest I ever went on one tank was 824 miles. For that tank, the fuel bar stayed full until 166 miles, when the top bar vanished. The bar was at the halfway point at 410 miles. The last pip flashed at 711 miles. That’s when I put a 2 gallon gas can full of fuel and a funnel in the trunk, just in case. DTE was 0 when I hit 733 miles. I just kept driving and driving. Eventually, I didn’t want to risk it anymore, so I filled up before I could run it empty. The pump automatically clicked off at 11.2 gallons, but I knew I could get a lot more in there. It eventually took 13.11 gallons, and the gas was all the way up and right at the neck where the gas cap goes. So, you can go pretty far after the last pip starts flashes. I went over 100 miles and didn't run it empty. Just my 2 cents.

     
  17. bwilson4web

    bwilson4web BMW i3 and Model 3

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    I appreciate this:
    The difference between theory and practice is having the fortitude to do the experiment. <grins>

    So, are you thinking about something like this?
    [​IMG]
    It is boring as heck and not a lot of fun.

    To reach the gas station, I added 1 gallon and the receipt was:
    [​IMG]

    Bob Wilson
     
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  18. 70AARCUDA

    70AARCUDA Active Member

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    Mr. Bob Wilson, you sound like one of those "Rocket City Redneck" scientists on the History Channel (ha,ha)!
     
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