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Fuel system - recirculating?

Discussion in 'Gen 2 Prius Technical Discussion' started by DJ Thomas, Jan 5, 2015.

  1. DJ Thomas

    DJ Thomas Junior Member

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    Does the Gen II Prius fuel system cycle fuel in a continuous loop past the fuel injector pump and back to the tank?

    If so, would the gasoline returning to the tank after the engine is thoroughly warmed up be warm enough to make the rubber fuel bladder more flexible and more likely to improve capacity?

    This from a convert from Jetta diesel who is used to having fuel preheated in the fuel filter for increased efficiency and less waxing.
     
    #1 DJ Thomas, Jan 5, 2015
  2. bisco

    bisco cookie crumbler

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    pretty tough to pull up to the gas station with a cold engine unless you live close by.
     
    #2 bisco, Jan 5, 2015
  3. DJ Thomas

    DJ Thomas Junior Member

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    True, but a significant portion of the fuel in the tank would have to have recirculated past the warm engine to warm up the bladder in the tank. Assuming any of this happens, we are probably looking at the best part of an hour or running to make a difference especially if the temperature is at -13 C. The strategy would be to fill up at the end of or well into a trip.

    The whole idea flounders if the system doesn't recirculate fuel so that is my base question, before I change my approach to refuelling timing.
     
    #3 DJ Thomas, Jan 5, 2015
  4. edthefox5

    edthefox5 Senior Member

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    No such thing as a fuel injector pump. Theres a fuel pump submerged in the fuel tank which keeps constant fuel pressure at the injectors. It pumps one way.
    No recycling of warmed up gasolene anywhere for any
    Reason.

    And what does "refueling timing" mean.

    Best way to mitigate fueling woes is just vent the tank.
    Take the cap off and go in the store. Come out and stick the pump in the hole and fill on slow. First click hang it up.

    In very cold climates do not run the tank really low.
    I would fill up at minimum 4 pips if freezing out.
     
    #4 edthefox5, Jan 5, 2015
  5. bisco

    bisco cookie crumbler

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    i think some diesels recirc the fuel past the injectors. pretty sure my old benz did.
     
    #5 bisco, Jan 5, 2015
  6. Patrick Wong

    Patrick Wong DIY Enthusiast

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    #6 Patrick Wong, Jan 5, 2015
  7. DJ Thomas

    DJ Thomas Junior Member

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    Thanks, Patrick.

    There seems to be little knowledge transferable from a Jetta life to a Prius life.

    Got it. Vent the tank. Fill up above 4 Pips in normal (-13C) weather and resist giving the one finger salute to the 4X4 honchos who insist on tailgating. That make Prius' disappear or speed up don'tcha know.
     
    #7 DJ Thomas, Jan 6, 2015
  8. Easy Rider 2

    Easy Rider 2 Senior Member

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    Even those that have a pressure relief return back to the tank don't really circulate fuel "past the injectors".
     
    #8 Easy Rider 2, Jan 6, 2015
  9. GregP507

    GregP507 Senior Member

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    At any rate, the temperature of gasoline is irrelevant in comparison to the temperature of diesel-fuel. Gasoline is not subject to most of the problems encountered with low temperatures, which can cause diesel-fuel to increase in viscosity, solidify or precipitate paraffins. A diesel is also more subject to the effects of temperature variations because it generally runs cooler than a gasoline engine, the engine block is usually thicker, and ignition itself depends on the heat generated by compression of air in the cylinder.
     
    #9 GregP507, Jan 6, 2015
  10. bisco

    bisco cookie crumbler

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    and that can really mess up the bladder!:mad:
     
    #10 bisco, Jan 6, 2015
  11. Janstheman

    Janstheman Junior Member

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    If I remember right, Prius may have a one way fuel system. For those that may not understand, for years fuel injection always delivered more than enough fuel to the injectors and if it did not use that fuel it was returned to the fuel tank to be used again.
    New thinking prevailed and now many cars have pulse width modulated fuel pumps. In other words, the pump is turned on and off very quickly by controlling the ground to the pump using the Powertrain Control Module. The less heat added to the fuel by the engine equals less fuel vapor being emitted by the tank at any given time. Vapors are bad, cool fuel is good.
    Just fill the tank the way the others have stated and you should have no problems. Park in a garage, no wind to drag away the heat that you have already generated. Good advise would be to add a block heater. That would add heat to your engine if not garage is available.
     
    #11 Janstheman, Jan 6, 2015
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