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Ran Out of Gas

Discussion in 'Gen 2 Prius Main Forum' started by TonyPSchaefer, Oct 14, 2006.

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  1. hycamguy07

    hycamguy07 New Member

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    Hmm, I have always had vehicles that got 6 - 17 mpg. :blink: So going from that to one that gets 45 - 56 mpg is awsome...! [​IMG]

    I took the trip from Orlando Fl to Bryan Tx on 22 gals of gas, in my prius. That was a total round trip of 44 gallons of fuel used :D

    My brother inlaw took the same trip and used 182 gals of gas, in a ram pick-up. He used 364 gallons of gas. :eek:

    Boy I glad we have the prius! B)
     
    #21 hycamguy07, Oct 14, 2006
  2. Bearcatzzz

    Bearcatzzz Junior Member

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    <div class='quotetop'>QUOTE(IsrAmeriPrius @ Oct 14 2006, 04:30 PM) [snapback]332861[/snapback]</div>
    You're right. I was barely awake and in a hurry this am. I was going to make some of the comments that others have made about pushing the flashing warning light, I won't pile on ;) .

    I was going to suggest 2 things:

    1) are the temps in his area dropping to the point where it influences the mileage?

    2) have they started delivering the winter mix fuel (assuming they do to your area)?

    This is my 1st winter with a Prius (OK I live in the Sac area and we really don't have winter here) :p , and haven't gauged the effects above. I know in other cars I've monitered the mileage, both things can influence the mileage up to 10%. This is within the range of your error.

    Just my .02
     
    #22 Bearcatzzz, Oct 14, 2006
  3. hdrygas

    hdrygas New Member

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    All I know is when my bladder is full I can not go as far between stops. Just fill it up when it gets low and the LTA will tell the tale. It is nice to brag on one tank but the fact is a 3 or 4 tank average is more reliable measure of how you are doing and running out of gas is a pain in the posterior.
     
    #23 hdrygas, Oct 15, 2006
  4. Skwyre7

    Skwyre7 What's the catch?

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    <div class='quotetop'>QUOTE(hdrygas @ Oct 15 2006, 12:24 AM) [snapback]332916[/snapback]</div>
    Taken out of context, this was a very funny statement. :lol:
     
    #24 Skwyre7, Oct 15, 2006
  5. richard schumacher

    richard schumacher shortbus driver

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    Trust the gauge, obviously. If the gauge is wrong (*), the worst thing that happens is you buy gas a few miles/days before you really needed to. If the MFD is wrong, you run out of gas and get stranded, burn up your fuel pump, et cetera. Which set of possibilities would you rather face? Take your time, think it through...

    (*) There are very few reports of the gauge stating that there is fuel when the tank is in fact empty
     
    #25 richard schumacher, Oct 15, 2006
  6. ken1784

    ken1784 SuperMID designer

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    Hi Tony,

    I see your frustration, but...
    <div class='quotetop'>QUOTE(TonyPSchaefer @ Oct 15 2006, 08:37 AM) [snapback]332863[/snapback]</div>
    You filled only 8.439 gallons last time.
    Why do you know you had more than 10 gallons?
    - It is wellknown that the MFD shows 2% or 3% better mileage displayed on MFD than actual.
    - Your safety distance was only 8.439*(61*0.97)=499 miles.
    - It is wellknown that the blinking timing is not consistent with actual.

    My suggestion is please understand your Prius before complaining it.

    Ken@Japan
     
    #26 ken1784, Oct 15, 2006
  7. TonyPSchaefer

    TonyPSchaefer Your Friendly Moderator
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    <div class='quotetop'>QUOTE(ken1784 @ Oct 15 2006, 01:36 PM) [snapback]333048[/snapback]</div>
    Oh Ken.
    I almost pick up a hint of hostility, but I'll accept it coming from you knowing that you've had your Prius as long as I've had mine.

    My "had more than ten gallons" comes from a history of several tanks. In order, they were this:
    08/02 - 10.782
    08/21 - 10.326
    09/14 - 9.555
    09/26 - 8.439

    Now, this either means that I consistantly have more and more gas remaining in my car at each fill-up (how I interpretted it) or that my bladder is shrinking (probably more accurate). I kept thinking about that 10.7 gallon tank thinking that I still had that much gas in the car. It's becoming clearer to me that I actually consumed all 10.782 gallons but could only refill with 10.3 gallons. So now we've proven beyond a doubt that the bladder shrinks. Of course, there are others who have reported this. I guess I just neened to see it and experience it in order to internalize it.

    So I'm going to grab hold to the belief that the MFD is always correct and that calcualting by hand is impossible since we will never know at any given time exactly how much gas is in the bladder, how large the bladder is at the current temperature, and whether the amount of gas pumped reflects the amount of gas used or the capacity of the bladder.
     
    #27 TonyPSchaefer, Oct 15, 2006
  8. mdmikemd

    mdmikemd Member

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    You know, I have the opposite problem.

    If I'm down one or two "pips" and I have the time, I'll fill-up. Once, when I got to drive the car for a whole month, I had the mileage # on the MFD up to 800 miles. I was trying to see how long I could go without getting it to reset. Most of my fill-ups were $5-6.
     
    #28 mdmikemd, Oct 15, 2006
  9. darelldd

    darelldd Prius is our Gas Guzzler

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    <div class='quotetop'>QUOTE(TonyPSchaefer @ Oct 14 2006, 04:37 PM) [snapback]332863[/snapback]</div>
    Yeah well... wait just a minute there, cowboy. I don't trust the silly guess gauge any farther than I could throw it. When we did our 1,500mi trip this summer, I found that on some days I could go 10 miles between the 3rd and 2nd pip, and other days I could to 60 miles. Scared the hell out of me to get down to one, as I was driving in unfamiliar territory. I ended up with an effective tank range of under 300 miles since I never wanted to find myself on one of those 10-miles-between pips days with no gas stations handy.

    I only WISH I could get familiar with this part of the car. I think the GAS gauge holds a grudge against me since we still favor the EV so much. In the EV, I know how much charge I have left to 1/10th of a percentage! In the Prius I roughly know about 25% at a time. And I'm still not even sure about that!

    <div class='quotetop'>QUOTE(ken1784 @ Oct 15 2006, 11:36 AM) [snapback]333048[/snapback]</div>
    Really? That almost makes it sound consistent. After recording every fill and all mileage for 5k miles, I've found that my calculated mileage is BETTER than the MFD estimate. By about 2%.
     
    #29 darelldd, Oct 16, 2006
  10. Sufferin' Prius Envy

    Sufferin' Prius Envy Platinum Member

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    I do my figurin' with how much I pumped in on that fill-up. If I only squeezed in 9.5 gallons, I do my expected range calculations off of 9.5 gallons. To assume you have a 11.9 gallons because you have a “full†tank is setting yourself up for a fuel bladder induced running-out-of-gas-episode <_< . . . especially if you do like TonyP did in driving 66 miles AFTER the ADD FUEL warning came on. :eek:

    Of all the displays and calculations to go on, I trust the ADD FUEL warning the most. Your Prius is telling you it is hungry . . . FEED IT!
     
    #30 Sufferin' Prius Envy, Oct 16, 2006
  11. Rick Grahn

    Rick Grahn New Member

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    I fill up at the lowest cost (non-Citgo) station regardless of what the gauge reads. Other than the weight of the fuel, what does it matter?
     
    #31 Rick Grahn, Oct 16, 2006
  12. molgrips

    molgrips Member

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    I don't have a bladder (in my car), and I have noticed that when the car tells you to add fuel, it really means it. Traditional cars with analogue fuel gagues always had plenty of gas left when they said empty. An old car I had had a seven gallon tank but would only take FOUR when the needle was on empty. So I got the flashing pip with the Prius, then drove maybe 20 miles, and when I filled up the tank had apparently only a couple of litres left in it. So when it says empty, it MEANS it!
     
    #32 molgrips, Oct 16, 2006
  13. Drifter

    Drifter Member

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    I was suprised to see this post. Tony has been around long enough to know better. So I suspect he was just looking for an opportunity to brag about his milage.

    For those who haven't been around as long, and if we assume Tony's post is sincere, the simple reason Tony ran out of gas is that he assumed he had 10 gallons of gas when he had only added 8.5 gallons at his last fill-up. With the temps as cold as they've been in Chicago this last week or so, I'm not sure how he thought that much extra gas would fit in the bladder but it seems to be a common misperception. So I reccommend either filling up at 2 pips (one if you prefer to push it) or calculating your expected milage based only on the gas you actually put in the car.
     
    #33 Drifter, Oct 16, 2006
  14. daronspicher

    daronspicher Active Member

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    <div class='quotetop'>QUOTE(TonyPSchaefer @ Oct 14 2006, 08:30 AM) [snapback]332689[/snapback]</div>
    Remind me... When you fuel up a 2004, does the MFD reset miles and overall MPG?

    On my 2006, if I don't push reset on the mfd, it will keep my mpg and just restart the miles ticker.

    Typically, I push reset when I gas up. A time or two, I gas up and find myself 5 miles down the road before I push the reset and decide to not push it, just let it go this time.

    If I do that, and my last tank mfd reading was 55mpg, but this time I'm buckin headwinds and hit a cold snap, I see my mfd reading creeping toward 52 by the end of the tank.

    Really, what I have is a much lower real mpg of about 46 or 48. So, if you have the same situation and dont' reset the mfd mpg average when you fill up, I could see how you could easily get into a much less efficient period and not get keyed in by the mfd mpg reading.

    If your 2004 resets automatically, then my theory is no good for your situation.

    I travel 90% of my miles (28400, 8.0 months) in chicagoland traffic on the tollways primarily ahead of the congestion commute in the 60-70mph range and average 52.xxmpg lifetime.

    Last weeks colder weather and stronger winds combined with about a 700 mile extra open road excursion got me about 1200 miles of 42 to 46 mpg miles to put a small dent in my lifetime average. It doesn't take much, just a 30 degree drop in temp, and 10 mph faster with cruise control on and wham, lower mpg returns.
     
    #34 daronspicher, Oct 16, 2006
  15. Charles Suitt

    Charles Suitt Senior Member

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    <_< Quote: "- It is wellknown that the MFD shows 2% or 3% better mileage displayed on MFD than actual."

    In 2+ years comparing hand-calculated MPG to the MFD computer numbers, the MFD on my Prius is close to Ken's quote above... actually as of yesterday, the MFD is 98.3% accurate compared to hand-calculated. For me, that's "close enough for government work" (to use a time-honored phrase).
     
    #35 Charles Suitt, Oct 16, 2006
  16. TonyPSchaefer

    TonyPSchaefer Your Friendly Moderator
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    <div class='quotetop'>QUOTE(Drifter @ Oct 16 2006, 08:21 AM) [snapback]333373[/snapback]</div>
    A fair assumption. :p
    But in reality, I was honestly surprised to have run out of gas. I thought I had the situation under control and thought I knew exactly what I was doing. Especially since it all had a happy ending with no personal or vehicular damage, I just thought I'd share. Additionally, because I was surprised, I wanted to put it before the community and have the conversation and discussions that we're having now.

    <div class='quotetop'>QUOTE(Drifter @ Oct 16 2006, 08:21 AM) [snapback]333373[/snapback]</div>
    The problem I'm just now figuring out, Drifter and everyone, is that using the "refill gallons" number is not a valid variable either. Looking at my last four tanks, 08/02 shows a refill of 10.7 and the largest variance with the MFD (61.0 vs 53.3) The reason for the discrepency is due to the expansion of the bladder in the August heat allowing me to pump in more gasoline than I actually consumed. This absolutely throws my calcualted numbers way off in the same way as the shrinking bladder causes less fuel to be pumped than was consumed.

    In my case, I realize now that I fell victim to the "Magically Shrinking Bladder." In my 53 tanks of gas over 26 months of driving, I never once had any reason to really consider it. So when faced with it, it didn't even occur to me.

    The problem is that I was viewing the situation from a statistical perspective without taking the bladder into consideration. Tank capacity represented a variable that I had previously been using as a constant.
    I very simplistically did this:
    "Tank-A accepted 10.7 gallons. Tank-B accepted only 10 gallons. Therefore, there was at least 0.7 gallons left in the tank. Tank-C accepted only 9 gallons. Therefore, there was at least 1.7 gallons in the tank since there was 10.7 at one point." (Unfortunately, attempting to chart the refill amount on my mileage chart does not provide any insight in to the capacity of the bladder in corretation to the ambient temperature.)

    Over the course of multiple tanks, I had simplified the situation to the point of convincing myself that I was "leaving" more and more gas in the tank after each fill-up. I even considered the possibility that the gas gauge was somehow recalibrating itself and resetting its "full" amount based on the refill amount. Of course, that would mean the less I refill with, the lower the recalibration. Sort of like early rechargable batteries that would hold less and less of a charge unless completely discharged.

    Aw screw it, I'm gonna so watch cartoons.
     
    #36 TonyPSchaefer, Oct 16, 2006
  17. galaxee

    galaxee mostly benevolent

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    whoa whoa whoa.

    you're all thinking about this waaaay too much. overthinking things leads to annoyances like... running out of gas. i used to way overthink things at work. it led to annoyances like screwing up my calculations and setting my plans back by a day. or forward by a day. either way, catching me off guard.

    when the car says add fuel, know that it means it. take the gauge with a grain of salt. that is all you have to do! don't make things so complicated ;)
     
    #37 galaxee, Oct 16, 2006
  18. TheProgrammerGuy

    TheProgrammerGuy New Member

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    Have you ever noticed that your car has something called a "gas guage"? Generally, when it starts getting below 1/4 tank I would think it is time to fill up...
     
    #38 TheProgrammerGuy, Oct 16, 2006
  19. TonyPSchaefer

    TonyPSchaefer Your Friendly Moderator
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    <div class='quotetop'>QUOTE(galaxee @ Oct 16 2006, 01:18 PM) [snapback]333536[/snapback]</div>
    I figured that there would be a few people who who truly understand that I was way overthinking the whole thing and worked myself into a mental tailspin. And I welcome the jovial ribbing from those with more than a couple score posts to their credit.
     
    #39 TonyPSchaefer, Oct 16, 2006
  20. bigdaddy

    bigdaddy Member

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    <div class='quotetop'>QUOTE(TonyPSchaefer @ Oct 14 2006, 09:30 AM) [snapback]332689[/snapback]</div>
    The power of the yellow snowflake is mightier than the MFD. Trust and follow the yellow snowflake until it disappears in April.
     
    #40 bigdaddy, Oct 16, 2006
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