Driving Past The Add More Fuel Beep

Judging from reports in the forums, there is wide variability in how long the car will run after the beep. Good for you so far, but next time it might be only 4 to 5 miles. If I'm low on fuel, I refuel before I hit a lonely road where there's likely to be no gas in sight. Why push your luck??

 

I realize that it is important to get a zero-tank in order to have fuel economy measurements that are accurate; however, driving when the tank is that low is extremely risky.

What I would recommended instead, is when you get the add fuel warning, pull into a gas station. Then, with the parking brake on, press on the gas pedal and brake pedal, and run the tank dry.

That way, before any of the serious stuff that happens when the tank is dry for more than, I don't know, a minute, begins to happen; you can fill it up right then and there, and you will be as close as you can possibly be to getting a fillup from zero.

 

The blinking pip is supposed to start at ~12% indicated per a post from Evan a few months ago, roughly 1/8th tank. Your results appear consistent with that.

In a normal car with analog gauge the empty line is at about 1/8th (looking at the scale and examining gallons added over many years) and the idiot light starts somewhere around then. I'm accustomed to running down to the equivalent of 5% of rated capacity on other cars, pushing it just as you describe--never had an out of gas situation that way...only at 25% indicated. It is MUCH easier in other vehicles since they don't have pips and the needle keeps going lower...while with the Prius the "needle" effectively disappears at 1/8th tank. Would love a digital gauge that showed something useful like actual percent. Dumbing the thing down is unhelpful.

Unfortunately the Prius has a bladder and complex tank gauge plus complex vent system that make its indicated tank level less reliable than other vehicles I've owned. So while applaud you for testing and reporting this, I'm not planning to push mine...at least not any time that I'm concerned about what happens if I run out of gas.

 

i went 120 miles past the blinking bar and 60 miles past zero on the DTE (distance to empty) on my 2010

if using luck, i would agree. better to know your car and driving habits. using the fuel amount you put in and the mpg's on the current tank is a better way of estimating how far you can go (assuming no one siphoned u!!)

and exactly why is this important?

forget the answer to the first question...after this line, i will pass on any advice you wish to offer

this is correct as verified by CANVIEW where the tank volume is display in percentage, but the graduations are actually at 2.5 % intervals so tank will measure

100
97
95
92
90 etc...

 

Just a reminder that 2010 does not have the bladder problem that previous model years suffer from.

 

It is important because gauging accuracy based on driving 500 miles with 8 gallons of gas versus 10 gallons of gas will lead to different results with either amount. One is more accurate. Don't you think?

Wow....would you maybe like to correct me with some helpful advice, instead of acting like a douche? Seriously.

 

Everyone needs a hobby, but surely there's something more fun than deliberately running out of gas.

 

Originally Posted by toxicity
What I would recommended instead, is when you get the add fuel warning, pull into a gas station. Then, with the parking brake on, press on the gas pedal and brake pedal, and run the tank dry.

oh sorry, i over reacted. i hadnt realized you meant that as a joke

if you look at the two quoted statements. in one you suggest that running a tank dry (hopefully you meant just real low) to get "better and more accurate" tank data

then right after that, you said wait until the last pip starts blinking.... then tie the car down in place and run the car until it runs out of gas as you watch your mpg's slowly drop to 30 something mpg.

 

Tempting fate is not worth enough to risk any expensive components in my car to see how far I can get before it tells me I need to put gas in it.

With the wide variation in fill volume due to the fuel bladder, it's even more risky.

I usually stop to fill when I get down to about 2 bars on the fuel gauge, usually around 400-450 miles.

 

i dont think it is, but i am hardly an expert of fuel pump dynamics (in fact i know nothing at all about them) but the blinking bar starts at about 12% of tank volume. that is over 1½ gallons. seems that would be plenty to keep something sitting at the bottom of the tank submerged

 

My guess would be that tank sloshing from car movement would tend to stir things up a bit, and the less fuel in the tank, the more that movement stirs up stuff at the bottom. I'll have to get a glass of water and see if that's really they way it works or not.

(I assume that the tank does not drain from the bottom, so there'll always be fuel below the level of the intake.)

 

actually i believe the fuel pump is an inline type and is situated slightly below the tank in a small funnel-like depression near the front of the tank which is also the way the tank is "tilted". so the likelihood of it being dry when the tank is low is not very high. the bottom of the tank is not flat

**edit**
i hit my blinking bar on Monday and will most likely be getting gas sometime today. (its my day off and i like the gas lines at Costco MUCH more on a thursday morning than a saturday afternoon!!)

i have probably waited until the blinking bar 80%+ times in all the fillups on the 3 Pri's i have owned. now granted, none of the 3 are old enough to have been filled enough times to make any determination on long term effects of practicing this habit. (thank you Pri for allowing fillups as much as 3 weeks apart!!)

now, not exactly sure how much i have in the tank, my DTE was around 42 miles when the blinker went off. last time i did a big fill, i went 60+ miles past the ZERO mark on DTE. probably wont be doing that today since i dont have enough errands today to drive that far. all driving today is basically in town for expected things to do today...will post results as always

 

When the PIP starts to blink there seems to be approximately 1 gallon of gas left in the tank. A variable that many do not consider is that it may depend on your current consumption rate on whether or not you can go 20 miles or 50 miles. You should also consider whether or not you have any cold starts or short trips. The only way I would trust it is if you were to press reset on the consumption screen right as you get the warning. Theoretically based on others testimonials you should run out of gas just as your MPG and miles travel are the same number.

 

An interesting thread all the way through.

( So, the last "pip" goes out and then the thing starts "beeping" at a certain point? Or does the last "pip" start "blinking" and "beeping" at the same time? )

As for me, I rarely let the "guess gauge" get below TWO pips ... especially on long, highway trips, when I can never be certain of how far it might be to the next gas station. The very last thing I want to do is run any risk whatsoever of running out of gas in a Prius.

And, as a side note to this thread: while I've kept a record of the display's MPG at every fill-up, I always use miles driven / gallons pumped to figure Mithril's "official" mileage. When the display itself starts paying for the gas, I'll take it's word for it ....

 

I drove my 2006 for a while and the last pip was not yet blinking and I put 11.625 gals so there can't be a gal left when it starts blinking. At least not in mine.

 

According to the manual it is 3 gal remaining, approx. when it starts blinking.

 

On my first tank after purchasing it used, I went 58 miles after it started blinking, pumped 10.2 gal and had 46.2mpg. I also think that on that last start up before filling, besides blinking it states get fuel. Another fill up 41 miles past blinking, added 10.55 gal. On the last fill went 38 beyond with 10.6 gal fill and no extra message to fill up. I think it is good to know what one's car is doing as it seems to vary so much?

 

I have had similar experiences on my experimentations so far after 4 fill ups. 1st one was after 58 miles past and a 'fill now' as well with 10.2 gal and 10.6 gal on the last fill with 38 miles past.