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

Does fuel economy affected by how much gas left in the tank.(full tank vs 3-4 bars)

Discussion in 'Prius c Fuel Economy' started by amilamad, May 9, 2015.

  1. amilamad

    amilamad Junior Member

    Joined:
    Jun 21, 2014
    15
    0
    0
    Vehicle:
    2012 Prius c
    Model:
    Three
    I read somewhere that the fuel pump is inside the fuel tank and its best to keep the pump drown in fuel for better fuel efficiency. Is this true ?.

    And does the fuel pressure affect the economy?.
     
    #1 amilamad, May 9, 2015
  2. JimboPalmer

    JimboPalmer Tsar of all the Rushers

    Joined:
    Apr 14, 2009
    12,470
    6,862
    2
    Location:
    Greenwood MS USA
    Vehicle:
    2012 Prius v wagon
    Model:
    Three
    The pump is reported to last longer when always covered by the fuel, but I have no reason to expect better fuel mileage.
     
    #2 JimboPalmer, May 9, 2015
  3. valde3

    valde3 Senior Member

    Joined:
    Jun 28, 2014
    2,002
    745
    0
    Location:
    Finland
    Vehicle:
    2004 Prius
    Pump will keep the pressure constant. So pressure will stay the same until there’s so little fuel in the tank that pump is sucking in air. Sucking in air will also shorten the life of the pump.

    So fuel economy will be the same regardless of amount of fuel in the tank. Except for the small effect that the weight of the fuel will have.
     
    #3 valde3, May 9, 2015
    amilamad likes this.
  4. jdenenberg

    jdenenberg EE Professor

    Joined:
    Nov 21, 2005
    3,837
    1,828
    1
    Location:
    Trumbull, CT
    Vehicle:
    2020 Prius
    Model:
    LE AWD-e
    The only impact on MPG is the weight of the gas in the tank. You would find it difficult to measure the affect of the small additional weight.

    JeffD
     
    #4 jdenenberg, May 9, 2015
    amilamad likes this.
  5. bisco

    bisco cookie crumbler

    Joined:
    May 11, 2005
    107,777
    48,984
    0
    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    this is an interesting hypothesis, i read it somewhere as well.:)
     
    #5 bisco, May 9, 2015
    amilamad likes this.
  6. wjtracy

    wjtracy Senior Member

    Joined:
    Sep 19, 2006
    11,314
    3,588
    1
    Location:
    Northern VA (NoVA)
    Vehicle:
    Other Hybrid
    Model:
    N/A
    Do I assume correctly this design is the same as all Prii at least Gen2+ ?
    We have had very few pumps replaced to my recollection.
    No mention of better MPG with fuller tanks from the experts (800 miles per tank crowd).
    Maybe this is one reason Toyota makes us fill the tank with still 2-3 gallons when the pip starts blinking
     
    #6 wjtracy, May 9, 2015
    amilamad likes this.
(You must log in or sign up to post here.)