I ran out of gas...

Discussion in 'Clarity' started by David in TN, Dec 31, 2018.

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  1. David in TN

    David in TN Well-Known Member

    Before I start this - I'm aware of the negative consequences of the items I'm about to mention. :)

    I was on the interstate the other day in HV mode. I was showing about 25 miles of EV remaining.

    I read in the manual that when the fuel light comes on, you have approximately 1.1 gallons left.

    With previous Honda vehicles, this can vary quite a bit, and from car to car. I had a Fit that showed 1.6 left, and I could run over 2.2 gallons and still have gas left.

    So, curiosity got the best of me. Fuel light turns on. I reset Trip "B" to 0. While paying attention to my MPG (around 42) I figure I should be able to go about 46 miles safely.

    I was approaching an exit, 46.2 miles on the trip meter since resetting, and warning messages start showing on the dash. The car switched to EV, and I was out of gas. It was about a mile to the next gas station.

    I FILLED the tank - every drop I could. 8.922 gallons.

    Several curiosities answered!

    After filling the tank, and turning the power back on, there were no negative messages.

    So - I learned that when it says 1.1 gallon left... on mine... I have 1.1 gallon left! Total fuel capacity, of mine, is 8.9 gallons.
    Hoon, SRCGTA and Electra like this.
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  3. jdonalds

    jdonalds Well-Known Member

    8.9 gallons is a surprise
    ClarityDoc and insightman like this.
  4. Ray B

    Ray B Active Member

    Hi David - when you say "every drop I could" does that mean including the fill pipe? In other words did you keep adding after the nozzle shut off automatically?

    Just curious...
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  5. David in TN

    David in TN Well-Known Member

    I filled it until no more drops could go in the fill neck.

    Sent from my SM-N960U using Inside EVs mobile app
  6. craze1cars

    craze1cars Well-Known Member

    This means you’ve learned that the capacity of your fuel tank, charcoal vapor canister, fuelneck, overflow tube, and all the lines connecting the entire system that are normally supposed to hold only air and fuel vapor, might have a net capacity of 8.9 gallons. And we don’t know how much liquid overflow went back into the stations vapor neck with each click of the pump past the first one.

    The car still has a 7 gallon tank.

    Should never top off a modern fuel system like that.

    Frequently doing this damages the car. And you have almost 2 gallons of unreachable fuel in the car now that will eventually evaporate into the atmosphere and never propel the car.

    Unlikely damaged one time, but don’t repeat this practice, it’s cumulative...

    When the pump clicks off, hang it up.
    Last edited: Jan 1, 2019
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  8. Viking79

    Viking79 Well-Known Member

    Yes, they don't exaggerate on that fuel low light like most vehicles. That is why getting the HV range software fix is so important, 1.1 gallons might not be enough range to reach the next station in a remote area.

    As others said, the tank is 7 gallons, might take up to 7.1. Either the gas station pump was lying or as mentioned you might have filled the other fuel system bits. Might try to run the engine for a while and see if you get any check engine lights.

    You shouldn't be able to fill those, but maybe if the car was positioned just right so the fuel could run into them. Are you sure it wasn't 6.9 gallons?
  9. Nemesis

    Nemesis Active Member

    Just to add to this thread. Glad you made it to a gas station. I am also guilty of adding more than 7 gallons to my Clarity. Never went to 8.9 but also never ran out of gas.
  10. PHEV Newbie

    PHEV Newbie Well-Known Member

    Wow, I've never been brave enough to let it get that low (even though I always keep at least 50% in the traction battery in HV mode). I once added a bit over 6 gallons during a fill up and I was really nervous before I found that gas station!

    BTW, going empty on gas was already discussed in the Clarity forum so it's worthwhile for folks to do a search before experimenting on their own cars : )
  11. craze1cars

    craze1cars Well-Known Member

    Just a couple things I cut and pasted out of the Honda Clarity owner's manual, page 452:

    "Do not continue to add fuel after the filler nozzle has automatically stopped. Additional fuel can exceed the full tank capacity."

    "When the tank is full, the filler nozzle will click off automatically. This leaves space in the fuel tank in case the fuel expands with a change in the temperature."
    (my own addition to this...not Honda's words: The 7 gallon capacity stated on spec sheets for any vehicle refers to the LIQUID capacity. Yes more can be jammed in -- but doing so has potential to defeat the entire evaporative emission control system by causing liquid to overflow into places where vapor belongs.)

    Link here to schematic of vapor canister...it sits right next to fuel tank:

    Breakdown of fuel tank parts:

    And here is the ungodly complex fuel pressurization system that the Clarity has, which causes the delay in fuel door opening when you push the button. This is all engineered due to the fact that they're expecting old fuel to be left in the system for long periods of time on these vehicles: (this is unique only to PHEV's...and most certainly you do not want liquid fuel to be forced into these parts which are tied into the fuel system, but designed to move ONLY air...). Click VIEW RELATED PARTS within this link to blow up the schematic:
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  13. craze1cars

    craze1cars Well-Known Member

    And if we haven't lost you yet, here is the whole story Honda provides to Clarity owners out of the owner's manual...I feel it's important that everyone needs to understand that PHEVs do not have normal fuel systems. These words do not warn of potential damage, but they do allude to the complexity of the system, and the importance of how Clarity manages (and needs) vapor in the fuel system:

    "This vehicle has a pressurized fuel system. When the fuel vapor pressure inside the fuel tank is high, it takes about 10 seconds for the vehicle to vent the fuel tank. Once the pressure is vented, the driver information interface changes from Please Wait to Ready. If the filler nozzle keeps turning off when the tank is not full, there may be a problem with the pump's fuel vapor recovery system. Try filling at another pump. If this does not fix the problem, consult an authorized Honda Clarity Plug-In Hybrid dealer. Do not continue to add fuel after the filler nozzle has automatically stopped. Additional fuel can exceed the full tank capacity. The filler nozzle automatically stops to leave space in the fuel tank so that fuel does not overflow as a result of changes in air temperature. If the fuel fill door does not open after you press the button, even after the display changes to Ready, you can manually open the door. 2 When You Cannot Unlock the Fuel Fill Door P. 562 An internal valve automatically closes after 30 minutes from the moment you press the fuel fill door release button. When it does, do not continue to refuel as fuel may spill out. When the fuel fill door automatically opens, a vent valve in the fuel system also opens to allow the air and the vapors being displaced by the fuel to escape. This valve automatically closes, however, if the refueling is not completed within 30 minutes. If this happens, reinstall the fuel cap, close the fuel fill door, and then follow these steps again to restart the system."

    Sorry so much -- I'm out now. Happy New Year everyone....
    Remarksman likes this.
  14. AlAl

    AlAl Active Member

    I've discovered that the GoM is pretty darn accurate in this car. Had about 35 miles left in the tank. Took approximately 6.2 gallons to fill.
  15. leehinde

    leehinde Active Member

    I had one episode where the car wouldn't let me add gas. It was early on in my Clarity ownership and the first time at that station, so I tried again at a different station and it worked. I haven't had the problem since.
  16. David in TN

    David in TN Well-Known Member

    When I said... "Before I start this - I'm aware of the negative consequences of the items I'm about to mention." I've read the manual. I'm aware of the issues of overfilling, running out of gas, and everything that has been mentioned. However, the engineering side of me wanted to satisfy my curiosity.

    This is my 22nd Honda product. I've owned a Honda product, continuously, for <gasp!> 41 years! I currently have five Honda products.

    My experience has been that gas tank capacity might be misleading. Using the "fill it until it can't hold another drop" method - we have a Pilot with a 20 gallon tank that I've put 25 gallons in. I had a CRX with an 11.9 gallon tank that I couldn't put 11.0 in it - ever - and I put over 300k miles on it.

    So -- I've satisfied my curiosity about:
    1) when the low fuel light comes on;
    2) the actual fuel capacity

    I'm not condoning this practice - but someone had to do it! :D

    The comments don't bother me, and I'm not going to jump ship. There are some great people on here, and I've appreciated most of what I have read on my short time here. I look forward to many more dialogs in the future!
  17. MNSteve

    MNSteve Well-Known Member

    The engineer in me says . . . Thank You.
    BuggaMom and David in TN like this.
  18. JulianClarity

    JulianClarity Active Member

    Good to know. I was told about 60 miles left and I put about 5.5 gallons in. It was weird, I saw there were 4 bars on my right. When my battery was empty and I think the tank got less than half left, my range dropped about 2 miles for each mile I drove.

  19. ozy

    ozy Active Member

    I'm assuming that running completely out of gas is not such a big deal if you have enough EV to get you to a fuel station? I used to have a CNG natural gas car and I would need to sweat it every day to make sure that the remaining miles were within range of a compatible station. I'm looking forward to never worrying about this again.
  20. oko

    oko Member

    Thanks for the engineering experiment of OP and the links from others. I learned new things. And I am a bit shocked. The county I grew up has no self service fuel stations. Credit cards are also not that common so cash is the king. And every time you fill-up your tank, almost without exception, the fuel is topped off, to the nearest currency amount. Every time... And it is usually topped off aggressively, several times, until that nice 40.00 or 50.00 shows up for the payment amount. And I have never seen anyone, any time, anywhere for the last 49 years of my life having a problem with "charcoal canister" or any other fuel system parts that the Angie's list article is talking about.

    Note that I never top-off mine here in US. And I understand the PHEVs have different systems. I am talking about regular cars (note that the article does not mention about PHEV at all).
    David Towle likes this.
  21. ryd994

    ryd994 Active Member

    There wasn't Clarity in the past 49 years either. (except the FCV)
    Plus, for such a place credit card not so common, you might be the first and only person owning Clarity or any other car with pressured tank.
    You don't want to be the first example of flooded charcoal canister, do you?
  22. JulianClarity

    JulianClarity Active Member

    I am running purely on gas, because I haven't got my charger yet.
    I get 49.3 mpg, what do you guys get?
  23. MPower

    MPower Well-Known Member

    I am very impressed. On my recent trip, I averaged about 42 mpg, with a lightly loaded car, running in HV, and starting each day with a full-3/4 full charge.

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