Ran Out of Gas

Out of curiousity, what did your gauge read?

 

:lol: its not the gauge or the MFD, it is a defect in the nut behind the steering wheel !

 

I think with the fuel bladder, the amount of gas you have when you fill up is not always the same, due to temperature difference and other variables such as the pump cutoff at the gas station. For example, I've filled up thinking I should be able to get at least 10 gallons in based on the MFD, but the pump cuts off after 9.2 or something and I can't squeeze any more gas in. Does that factor in?

 

if you average out your mfd readings and compare them to the average of your calculated readings, they're only off by about a half mpg. I'm sure if you averaged all your readings and compared them they'd be closer. My calc vs. mfd mpgs agree to 0.05 mpg, although I also have individual readings that differ by 5 to 10 mpg.

I believe it's the bladder, and how you fill it. I trust the mfd more than the calculted value.

 

<div class='quotetop'>QUOTE(Prius Maximus @ Oct 14 2006, 09:34 AM) [snapback]332706[/snapback]</div>

I agree. The first thing I did was average Tony's numbers. Shows that over the six readings, what the MFD showed and what Tony calculated differed by only .73 mpg.

Tony: You have indeed fallen into the bladder trap. Probably the one "reliability" issue the Prius has. You cannot rely on the capacity of the bladder always being the same. It will vary some with every fill-up and that variance can be as much as a gallon - though more likely less than .5 gal.

When you are getting 50-60 mpg or more, a variance of even one quart of gas will show the kind of differences you see in your calculated numbers. Average your calculations and the MFD calculations to prove it.

I usually fill my Prius when the gauge gets down to four, maybe three pips (I think that's what people around here call the marks on the gauge). Somtimes I let it get down to two. I have seen my "range to two pips" vary by nearly 100 miles.

Trust the gas gauge to tell when the car is low on gas. Though there are people that have reportedly gone from two pips to out of gas in short order so I wouldn't wait till one pip is flashing. Because of temperatures, pump shut off settings (which can differ at the same gas pump depending on delivery flow/pressure), maybe even even barometic pressure and a few other things, you cannot trust the gauge to tell you that bladder is really "full" (at its rated capacity).

Trust the MFD to give you accurate gas mileage numbers, but remember that it is not using the bladder capacity to do the calculation.

 

As a side question does anyone know how long I can reliably run when it hits one pip. Is even 10 miles questionable? 15? 20? There must be a safe answer. Sure I could fill it up now but I would like to see how many miles I can get on a single tank without being stupidly\dangerously low on gas.

 

" Out of curiousity, what did your gauge read? " Do these things come with gauges?

<div class='quotetop'>QUOTE(Curtis SAC @ Oct 14 2006, 11:27 AM) [snapback]332726[/snapback]</div>

I usually fill up around 2 pips myself - I would estimate that about a 1/4 of a tank which is when I generally fill up in my other cars.

 

<div class='quotetop'>QUOTE(Beryl Octet @ Oct 14 2006, 10:27 AM) [snapback]332704[/snapback]</div>

The 04's dont have this tank bladder problem that I know of, every fill up its 11.9 gal.

I think its the math, (to many varibles) I always fill up at one pip thats 511 miles.(remember your mileage will vary due to your driving habbits) or when the one pip starts to blink I head for the closest gas station. As for the chart, the calculated numbers are bouncing at least 10miles etheir side of the mfd. (10 miles will make or break you in this car)! B)

 

I don't get how people keep runnign out of gas. The low fuel warning comes on, the gas gauge last pip starts blinking, and people still don't get gas!

Worry about how much gas the MFD thinks you should have after a fillup.

I once ran out of gas in insane Friday traffic in Dallas, TX. I was stuck ni the left lane for so long I just ran out. I walked to a gas station and put 1 gallon in the only spare tank they had. I had to wait by the highway for 6 hours in the heat before the traffic was light enough for me to head for a gas station. I ended up stuck about thre hours south of home because my fuel pump burned up.

Now I fill up with two bars left like clockwork.

 

<_< Quote: "... The 04's dont have this tank bladder problem that I know of, every fill up its 11.9 gal. ..."

My '04 varies a bit from tank to tank, but overall it calculates >98% accurate compared to manual calculation. I always fill at one non-blinking pip. I've *NEVER* been able to pump more than 10 gallons. I chose to *NOT* have the TSB done for "Fuel Gauge Inaccuracy" in early 2005 due to the extensive tear down/re-assembly procedure and reports that doing it only rarely made the "guess gauge" more accurate.

 

<div class='quotetop'>QUOTE(Boxster...WRX...Prius? @ Oct 14 2006, 01:35 PM) [snapback]332758[/snapback]</div>

You know, this is the simplest idea to follow and you dont have to dammage anything pushing the car to its limits.

Fill-up at 2 PiPs!

 

You obviously have a terrible Prius. You average 60mpg, get 566 miles out of a tank. I would sell it if I were you. So far I haven't gotten more than 450 miles out of a tank, ran out of gas once at 422 and my average per tank has never been over 45 mpg. I pulse and glide until I get motion sickness, have my tires at 40/38. But yours, there is something wrong with it, I am sure...

 

<div class='quotetop'>QUOTE(Tony_Min @ Oct 14 2006, 04:20 PM) [snapback]332815[/snapback]</div>

You know there are several factors that come into play regarding our MPGs.

1. Terrain

2. Weather/Temp

3. Driving style/ road conditions

4. city/hwy differences

Maybe thats why the japanes did thier factoring ina more controled setting... I notice everyone tries to get better mileage & push the envelope. But in reality the car gets the best MPGs better than the other cars in its class...

 

Oh I know. I live in Northern California where there is no flat terrain. My car has only 1600 miles on it and I have been doing mostly short trips. Still, even taking those things out of the equation I wouldn't see getting much more than 50mpg.

 

<div class='quotetop'>QUOTE(TonyPSchaefer @ Oct 14 2006, 09:30 AM) [snapback]332689[/snapback]</div>

 

<div class='quotetop'>QUOTE(Stan57 @ Oct 14 2006, 06:37 AM) [snapback]332692[/snapback]</div>

Your question was answered in the original post:
<div class='quotetop'>QUOTE(TonyPSchaefer @ Oct 14 2006, 06:30 AM) [snapback]332689[/snapback]</div>

The Add Fuel warning show on the MFD when the last bar on the fuel gauge starts to blink.

 

<div class='quotetop'>QUOTE(Charles Suitt @ Oct 14 2006, 10:52 AM) [snapback]332765[/snapback]</div>

I didn't have the Fuel Gauge Inaccuracy done on my 2004 for the same reason, but I have never come close to getting 10 gallons in the tank. I went all the way to the last bar blinking this week and was only able to put in 7.5 gallons. I can still get close to 400 miles on one tank, so I'm not complaining. The display read 54.9 and calculated was 53.3. I just passed 30,000 miles. I've recorded every fill-up. The average display is 53.65 mpg and the calculated is 52.54. The average amount of gas I've put in the car is 7.22 gallons.

 

<div class='quotetop'>QUOTE(TonyPSchaefer @ Oct 14 2006, 07:37 PM) [snapback]332863[/snapback]</div>

Ah, but it is both. The catch is, the Prius will only tell us one or the other. And it switches depending on it's mood. That is where the variability comes in. Sometimes it tells us the correct milage, hence the first pip disappearing after 150+ miles. Other times it tells us how much gas in the in tank, hence this thread. Or, it could be guessing at both an occasionally gets one or the other right.