1. Attachments are working again! Check out this thread for more details and to report any other bugs.

First try at a Mega-Fill

Discussion in 'Gen 2 Prius Fuel Economy' started by priusham, Jul 27, 2005.

  1. priusham

    priusham New Member

    Joined:
    Jul 6, 2004
    525
    1
    0
    Location:
    Michigan - land of everlasting snowflake icon!
    Yesterday, I tried my first "mega-fill" where you pump > 11.5 gallons into the Prius.

    As you can imagine, it really screwed up my :guns: MPG reading for the tank! :cussing:

    http://www.w8kc.com/priusmileage.htm

    The previous fillup was done by my wife without me in attendance. I'm pretty sure she simply stopped putting fuel in the car when the pump hit the auto shutoff point.

    I still had ONE BAR showing!!! Not even flashing! So that's really strange that (in theory) I was less than 1/2 gallon from running out of fuel.
     
  2. tomdeimos

    tomdeimos New Member

    Joined:
    Feb 16, 2004
    995
    2
    0
    Location:
    Lexington, MA
    I got my first big fill up: Got 12.3 gallons in.
    Got about 200 miles on it before the tank stopped reading full.
     
  3. DaveinOlyWA

    DaveinOlyWA 3rd Time was Solariffic!!

    Joined:
    Apr 13, 2004
    15,140
    611
    0
    Location:
    South Puget Sound, WA
    Vehicle:
    2013 Nissan LEAF
    Model:
    Persona
    on your mega fill, how much more did you put in after first click off when filling at slowest speed?

    i think inquiring minds would like to know what to shoot for if they try it.
     
  4. rflagg

    rflagg Member

    Joined:
    Jan 5, 2004
    947
    9
    0
    Location:
    Springfield, VA
    Dave,

    Usually, with a decent pump, it's around 1-1.5 gallons - for me, anyways.

    -m.
     
  5. tomdeimos

    tomdeimos New Member

    Joined:
    Feb 16, 2004
    995
    2
    0
    Location:
    Lexington, MA
    For my click off I don't remember what it was. I always fill way past it in any case and it happens sometimes at 3 gal and other times at 10 gal. My normal fill is generally a min of 10 gallons.

    The thing I did differen this time is followed instructions from Ray I think? to fill to gurgle.
    Couldn't do it with nozzle in so I pulled it out as far as possible. Side holes were out of gas so no way they could suck gas back into station tank. Then it could flow steady till I heard the gurgle meaning full. Stopped at put on cap as it sounded like it might spit. So didn't fill it to point of seeing the gas in the pipe.

    If we had nozzles with the big boots, I doubt I could get the car within 4 gallons of full, plus it would be riskier by muffling the gurgle noise!
     
  6. DaveinOlyWA

    DaveinOlyWA 3rd Time was Solariffic!!

    Joined:
    Apr 13, 2004
    15,140
    611
    0
    Location:
    South Puget Sound, WA
    Vehicle:
    2013 Nissan LEAF
    Model:
    Persona
    they require the boots around here. it really can suck sometimes. my ex had a real issue with new ones. couldnt get the nozzle in far enough for it to run. she hated em.

    she used to go to this one station that had the old pumps with no seal at all on em. she almost cried when they finally upgraded their pumps. (dont know why because i filled her tank about 90% of the time anyway)
     
  7. Prius-a-rama

    Prius-a-rama New Member

    Joined:
    May 15, 2005
    31
    0
    0
    I've seen different topics about filling the gas tank, but I'm curious to know if there's any negative aspects to "super-filling"?

    Beside the risk of spiling gas on your paint job, could there be a pressure build up issue that's bad for the car?

    I've only been able to get about 8 gals in when I drop down to 1 bar, and have therefore been only getting around 360-370 miles between fill ups.
     
  8. priusham

    priusham New Member

    Joined:
    Jul 6, 2004
    525
    1
    0
    Location:
    Michigan - land of everlasting snowflake icon!
    On the website in the original post for this thread, I do track the pump "auto-shutoff value" as well as how much I put in after that.

    This mega-fill was the first time I squeeezed in more than about half a gallon. It turned out to take over one gallon beyond the auto shutoff point.

    My average mileage is not high enough to go for a 700 mile tank. I'm leaving well enough alone.

    Isn't this car too much fun?
     
  9. DonDNH

    DonDNH Senior Member

    Joined:
    Feb 3, 2004
    1,711
    654
    0
    Location:
    Nashua, NH
    Vehicle:
    2016 Prius
    Model:
    Four Touring
    When you need to fillup again, let us know how the milage was for the tank AND whether you did another Mega-fill or just normal.

    If you do a normal fill the MPG will be very high for this tank and if another Mega-fill just about your normal MPG. In short, no effect at all on overall average.
     
  10. DaveinOlyWA

    DaveinOlyWA 3rd Time was Solariffic!!

    Joined:
    Apr 13, 2004
    15,140
    611
    0
    Location:
    South Puget Sound, WA
    Vehicle:
    2013 Nissan LEAF
    Model:
    Persona
    i dont think there are any real negative repercusssions with superfilling as long as you dont spill any of the gas. plus it seems to stretch your bladder allowing for larger and larger fillups. look at Ray and his fillups. he routinely gets 12+ gallons in his tank and he has been "filling it to the brim" since day one.
     
  11. Prius-a-rama

    Prius-a-rama New Member

    Joined:
    May 15, 2005
    31
    0
    0
    Okay, I'll try the mega fill on my next tank and try not to cop out after the first two autostop clicks.

    Oooooh, so frightening!
     
  12. seasidetraveler

    Joined:
    Apr 25, 2005
    662
    14
    0
    Location:
    CA
    Vehicle:
    Other Non-Hybrid
    Model:
    N/A
    I may be naive, but isn't the Prius tank only 11.5 gallons? How do you get over 12 gallons in that small of a tank??? I am confused
     
  13. Karkus

    Karkus Junior Member

    Joined:
    May 9, 2005
    38
    1
    0
    Location:
    Boulder, CO
    Vehicle:
    2019 Prius Prime
    Model:
    Prime Advanced
    Negative consequences have been discussed before on various boards
    1) Spilling gas (so much for that PZEV rating)
    2) Air pollution due to not putting in nozzle all the way
    3) Over-filling floods the vapor recovery cylinder in your Prius (and may cause damage and/or low MPG since it has to clear it out)
    4) Overfilling can cause gas to go into the vapor recovery system tube on some gas pumps, so you're not getting all the gas into the tank that you think you are (and you're wasting money). Prius owners haver reported being able to get free gas out of pumps where the previous person tried to overfill.
    5) It screws up the vapor recovery system on the pump, so the next Prius owner has trouble with the auto-shut off.
    6) Bladder in tank may compress when temperture changes after fill up, causing a gas spill

    I can't personally say that all of these are always true, but I think enough of them apply to make overfilling a bad idea in my opinion.
    For those of you who bought the Prius in part for its low emissions, it's definitely not cool to overfill. :(
     
  14. Tideland Prius

    Tideland Prius Moderator of the North
    Staff Member

    Joined:
    Oct 2, 2004
    44,899
    16,123
    41
    Location:
    Canada
    Vehicle:
    Other Non-Hybrid
    Model:
    N/A
    It's 11.9 US Gal.
     
  15. priusham

    priusham New Member

    Joined:
    Jul 6, 2004
    525
    1
    0
    Location:
    Michigan - land of everlasting snowflake icon!
    Update... as if anyone really cares...

    The first bar of the guess gauge finally went off somewhere just past 200 miles since my mega-fill. MFD shows 52.9 Avg MPG.

    It typically takes about 100-120 mile to lose the first bar.

    The Prius is a real mind twister... my old car, at 225 miles, I'd be thinking about buying about 12 gallons of gas in about 30 more miles!
     
  16. Tideland Prius

    Tideland Prius Moderator of the North
    Staff Member

    Joined:
    Oct 2, 2004
    44,899
    16,123
    41
    Location:
    Canada
    Vehicle:
    Other Non-Hybrid
    Model:
    N/A
  17. priusham

    priusham New Member

    Joined:
    Jul 6, 2004
    525
    1
    0
    Location:
    Michigan - land of everlasting snowflake icon!
    Sure... we are sitting at 1/2 tank this evening with @340 miles on the MFD ODO since mega-fill. 53.6 MPG AVG.

    Here's a fun fact. Today I stopped at TWO gas stations but never bought gas (didn't need it). The first was just to wipe some scum off my side window. The second time was to buy me and the kids slushies.
     
  18. twdusa

    twdusa New Member

    Joined:
    Mar 29, 2005
    53
    0
    0
    Location:
    Eastern North Carolina
    Way to go priusham!! Looks like you are well on your way to your best tank! I just have to ask......what is your tire pressure? Maybe think about trying 42 front and 40 rear? I think your MFD mpg will improve with those pressures. Let me know! Keep posting your results. I hope you get over 650 on this tank!
     
  19. dstrout

    dstrout New Member

    Joined:
    Apr 17, 2005
    64
    1
    0
    Location:
    Gaithersburg, MD (suburb of Washington, D.C.)
    Ha! Now that's funny. I accidentally dicovered the "mega-fill" today when filling up at a gas station in Outer Boondockia, OH. that had steam-powered pumps. The shut off kept tripping as it was pumping, so I just put the tip of the nozzle in and pumped til it gurgled up the fill neck. No spill, though. I put in 10.6 gal and had just dropped to one bar before filling up.

    It took me 200 miles to use up the first bar. I thought I had broken my gas gauge :(

    dave.
     
  20. priusham

    priusham New Member

    Joined:
    Jul 6, 2004
    525
    1
    0
    Location:
    Michigan - land of everlasting snowflake icon!
    I need to check the tire presure... been meaning to do that too! I usually run 42/40 +/- I really doubt I'll get much if anything over 600 miles. It's only these 1 hour trip up to my cottage (twice this weekend) that I see the super 55 MPG averages required for 600 + mile tanks.

    dstrout, what is that avatar? Looks like a car from the current sci-fi movie "The Island." It was filmed in Detroit - GM and DCX both got a ton of cars and prototypes in the movie.

    My brother and his wife were extras and both ended up in the film - which was pretty cool.