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

Is topping off the fuel tank bad for your Prius?

Discussion in 'Gen 3 Prius Fuel Economy' started by bennela, Nov 29, 2010.

  1. MrPete

    MrPete Active Member

    Joined:
    Oct 26, 2011
    390
    150
    20
    Location:
    Colorado, USA
    Vehicle:
    2011 Prius
    Model:
    Two
    I don't know about the pumps where you live (or maybe it has something to do with living at 7,000 ft?) ... I frequently encounter pumps that click off VERY prematurely, without any doubt.

    In other words, what counts as "topping off"?

    If the tank accepts over a gallon more by restarting, to me that doesn't seem like topping off. ;)
     
  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
     
  3. ColoradoBoo

    ColoradoBoo Senior Member

    Joined:
    Jul 19, 2019
    904
    593
    4
    Location:
    Monument, Colorado USA
    Vehicle:
    2017 Prius
    Model:
    Two
    That's true...if the underground tanks are full the pumps really go fast. I usually let the thing fill on the "fast" mark then, when within a few gallons of full, I switch it to the "slow" fill and wait for the auto stop.
     
  4. vvillovv

    vvillovv Senior Member

    Joined:
    Mar 19, 2013
    3,493
    1,231
    1
    Location:
    NY
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Plus
    It's sure not like it used to be. The old way of knowing a cars tank was full was when gas ran down the quarter panel or shot out of the fill hole behind the rear license plate.
     
    ColoradoBoo likes this.
  5. CR94

    CR94 Senior Member

    Joined:
    Dec 2, 2014
    2,642
    1,133
    0
    Location:
    Northwestern S.C.
    Vehicle:
    2011 Prius
    Model:
    Two
    The very same topic came up here not long ago. The short answer is that filling the tank that full causes damage. That degree of overfill normally takes at least about two gallons after the pump shuts off. Significantly lower amounts might not cause damage. Use common sense. Sometimes I add 1.5 gallons, but only if I won't be leaving the car parked on a warm day before burning off at least half a gallon. That has not caused problems.
     
    #25 CR94, Jan 14, 2023
    Last edited: Jan 14, 2023
    GregC1979 likes this.
  6. vvillovv

    vvillovv Senior Member

    Joined:
    Mar 19, 2013
    3,493
    1,231
    1
    Location:
    NY
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Plus
    The only way to know is to get the diagram of the fill pipe and it's assorted secondary tubes, than locate by looking at the filler tube where the breather tubes are on the specific model prii you own.
     
  7. tonynap

    tonynap Member

    Joined:
    Jan 13, 2019
    43
    37
    0
    Location:
    NY
    Vehicle:
    2012 Prius
    Model:
    Two
    I've topped up every tank since 2012 without incident.

    Your charcoal may vary
     
    ASRDogman likes this.
  8. qdllc

    qdllc Senior Member

    Joined:
    Aug 25, 2013
    1,358
    395
    0
    Vehicle:
    2013 Prius
    Model:
    Two
    Fill until it shuts off. Wait a few seconds, pump slowly until it shuts off. That’s all I’ve ever done. Sometimes full speed pumping causes a backwash that shuts off the pump (good), but so long as you aren’t pulling the nozzle out to go higher than that, you should be fine.