Any issues with EV driving with the Low Fuel Light for a long period?

Discussion in 'Prime Main Forum (2017-Current)' started by noonm, Nov 4, 2019.

  1. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    For myself, I would not have risked the health of my car for that, but perhaps buying another car does not worry you.
     
  2. Trollbait

    Trollbait It's a D&D thing

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    He isn't driving with an empty tank. From reports of past Prii behavior, there would be more than a just the low fuel light lit up if that were the case.
     
  3. bisco

    bisco cookie crumbler

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    don't try to explain it to jimbo, he's too worried about his mother in law
     
  4. Zed Ruhlen

    Zed Ruhlen Member

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    The real concern is not the fuel but the fuel pump. The fuel pump is cooled by the gas in the tank and can overheat without fuel. That would lead to a lower life of the fuel pump.

    Since the fuel level is completely unrelated to the MPG why would you care when you fueled? It would still say 500mpg
     
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  5. Trollbait

    Trollbait It's a D&D thing

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    With Toyotas, the tank average MPG display is automatically reset when fuel is added.
     
  6. Salamander_King

    Salamander_King Senior Member

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    Humm, do we have that feature in PRIME? I can't remember seeing mpg for tank average displayed anywhere. I think DTE is tied to this data but it is not displayed as MPG. And OP is using TripA to record the current tank MPG, as long as he does not reset it, it will continue to update the MPG whither tank is filled or not.
     
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  7. noonm

    noonm Active Member

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    I'm using trip A to 'calculate' the mpg so I can have the 500mpg for that one tank.

    Also, unless I'm missing something, I don't think the fuel pump should overheat because its (1) cold outside and (2) without the engine on, there really shouldn't be any heating of that area. Is there another source of heat I should be worrying about?
     
  8. Rob43

    Rob43 Senior Member

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    Fuel Pumps:

    Typically speaking, your only real fear about potential premature fuel pump failure is when you actually starve it of fuel while it's pumping. When a fuel pump is operating, the gasoline is its lubricant. If you starve it of its needed lubricant even for an extremely short period of time they sometimes fail.

    So when the ICE is running, your fuel pump needs fuel to keep it lubricated. If not, you might experience a bad day....


    Rob43
     
  9. Zed Ruhlen

    Zed Ruhlen Member

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    Where? I don't see any mileage number associated with tank on my display. I get a Trip A, Trip B, ODO, MTE ICE, MTE Battery, Current trip avg
     
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  10. Trollbait

    Trollbait It's a D&D thing

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    On my Camry, there is a small display between the tach and speedometer. I can toggle through a tire pressure display and three customizable screens. I currently have instant MPG, trip MPG, tank MPG, lifetime MPG, average speed, and a digital speedometer to just fill that last spot. I think it can also display the map if you have the nav system.
     
  11. VTBIGDOG

    VTBIGDOG Active Member

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    I think he meant to say that the DTE...Distance to Empty... automatically resets.
    Posted via the PriusChat mobile app.
     
  12. Rob43

    Rob43 Senior Member

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    I might need to "give in" and go to the gas station for 4 or 5 gallons of E0 gasoline real soon, I've been running on a low fuel light for the last ~8 days and 0% fuel on the fuel gauge....


    Rob43
     
  13. jerrymildred

    jerrymildred Senior Member

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    Sounds like it's worth a shot, but but too much tension for a routine practice for me. It looks like you're still nowhere near empty yet. Due to a ridiculous and unexpected distance between gas stations on our vacation trip this past May, we ran ours WAY past "empty." I was sweating bullets. When we finally got to a gas station, it only took 10.26 gallons to fill it.

    Not all Toyotas. Prime has no tank average and the only one that resets itself is the "since last start" average that resets every time you shut off the car.
     
  14. fuzzy1

    fuzzy1 Senior Member

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    That recommendation comes from the old days when fuel tanks were vented and had some air exchange with the atmosphere, not fairly well sealed as required by today's evaporative emission control requirements. PHEV tanks are sealed even better than other cars, so even less moisture can get in anymore. Even at maximum humidity, the replacement air coming in as the fuel level drops brings in only minuscule amounts of moisture. Combined with large amounts of gas line dryer ethanol in the fuel, that small amount of moisture ought to be easily tolerated.
    Does the fuel pump even operate when the Prime is running 100% EV mode?

    Even on non-plugin Prii, BobW intentionally ran his Prii out of fuel more than 50 times. Anyone remember how much he spent on fuel pump replacements? ;)
    Anxiety is in the mind of the beholder. I don't understand why someone driving a PHEV in essentially all-BEV mode, and thus presumably on trips within BEV range, should have any anxiety about the dinosaur fluid getting low in the tank. Plenty of true BEV drivers are out there without any dinosaur fluid tanks at all, and they don't seem to be having anxiety attacks about it.

    As for anxiety about a yellow warning light on the dash, some are simply irrelevant to the driver's particular usage and needs. For OP, this example fits. For me, it is a disabled-clutch-hill-holder warning on my Subaru. Having driven clutched vehicles without this feature for 5 decades now, my clutch foot reflexes simply work better with this feature turned off, regardless of the permanent yellow warning light.
    I still don't see anything about OP actually letting it run out.

    Actually running dry in a Prime might be a problem, in possibly shutting down EV operations too. But OP isn't necessarily running that low.
     
    #34 fuzzy1, Dec 1, 2019
    Last edited: Dec 1, 2019
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  15. noonm

    noonm Active Member

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    The only anxiety I have is that the 25mi (closer to 20mi in the winter) pushes the edges of how much I drive on a weekend day to do shopping, errands, etc. Most full BEVs have at least 100mi ranges, which would more than cover all of my needs except long trips.

    In truth, I prefer running my Prime with as little fuel as I think I'd need as that means less weight carried around = greater EV efficiency.
     
  16. Trollbait

    Trollbait It's a D&D thing

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    Most of the water in the fuel got there before it entered the car's tank. Deliveries to the station don't wait for it to stop raining or snowing, or the pavement to dry before unloading.

    Water in the ethanol will actually protect any aluminum components from corrosion.
     
  17. Zed Ruhlen

    Zed Ruhlen Member

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    Ahhh, yes.
     
  18. Zed Ruhlen

    Zed Ruhlen Member

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    So ethanol will absorb some moisture but water in a gas station's tank will NEVER be in the gas because they don't emulsify. You can't dilute gas with water. Gas floats on top of water. The water will be in the very bottom of the tank. There are no doubt water separators as well.
     
  19. Trollbait

    Trollbait It's a D&D thing

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    It does get sloshed around when filled.

    But more importantly, the ethanol is added to the gas before it gets to the station, so the water is emulsified with the fuel there. Barring there being enough water to cause phase separation, but stock turnover should prevent that. A station with alcohol free gas would need to monitor the water level as it increases with time until it gets picked up by the pump and could overwhelm the separators.

    Ethanol is hygroscopic, but under normal conditions its concentration levels off at 95.4% through addition of water through humidity alone. Any water portion greater than 4.6% in the ethanol portion of gasoline got there as a liquid that entered the supply stream. Humidity and condensation in a car's fuel tank will be a small addition.
     
  20. noonm

    noonm Active Member

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    500+ MPG achieved!

    [​IMG]

    I'm going to keep going as I still got roughly another week before I'm going to take a trip long enough to need to fill up my tank.
     
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