Ran out of gas with 9.5 gals out !?!?

It's a clever way of getting newbies to sound off. Not really, but fortunately this story ended at the right place.

Why do so many feel the need to push beyond the "Add Fuel" warning?
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I'm confused, was there a problem with the fuel gage or low fuel warning?

 

How do you know it was at 9.5 gallons? With the U.S. version of the Prius, there is no way to know how much usable fuel remains in the tank. The tank bladder causes the usable capacity to vary with temperature, age, and possibly phase of the moon. There is no way to ever know for sure.

Incidentally, the usable capacity of the U.S. Prius tank is never 11.9 gallons. That is the gross capacity. I usually figure that it is about 10 gallons, although most people can get a bit more out of it than that, but why push it. The real secret is to use the gas gauge; when it tells you to get gas, get gas.

Tom

 

I just filled up my first time today. there were two pips left after 370 miles. it only took 8 gallons, so I was happy. touch screen told me I averaged 48.1 mpg. not bad for a first tank in 35F weather.

 

I just wonder how many times did people run out of gas in their previous vehicles?

 

Experienced the same here. Since then, I always make sure I hit the gas station as soon as I see the fuel gauge light warning and beep. Prius tank capacity is very unpredictable. Most of the time I fill around 9galons, some day I fill even 8gal and one time to my surprise I was able to fill only 6gals. I think each gas station pump's sensitiveness counts too.

 

Hi rj-king,

Your the first that has said he/she ran out of gas with 3 bars still showing. As far as 9.5 gallons, well, when it gets down to 0 F around here we are lucky to be able to get 8.5 gallons into the tank. The Prius has a rubber bladder in the tank. It shrinks and gets stiff in cold weather, which prevents full fillage. But, it keeps damp air out of the gas tank too, so when it goes from 45 to 20F there in CT a few times a week you wont end up with water in your fuel system, and frozen injectors when it really gets cold.

So, let me get this straight, you say the car ran out of gas but was still showing three bars on the gauge ? The usual newbie report is that the gauge was blinking, and they knew it was a 11.9 ga tank, so they knew they had another 100 miles (2 gallons) left, when they ran out of gas.

What was the miles and fuel economy on your MFD when it ran out of gas ?

 

I think he meant 3 bars on his battery meter showing...

 

Looks like somebody else discovered the hard way why we call it the "guess gage".

 

something to remember- if you live in a cold climate, the bladder may shrink and hence, hold less fuel in the cold weather. why push it????? I was taught that in cold weather it is far better to keep the tank FULL to keep out moisture...

 

It isn't a guess gauge, it accurately predicts that you will run out of fuel if you don't add fuel. I am still waiting to hear from the PriusChat member who ran out of fuel with 2 or more bars lit on the fuel gauge. In fact I haven't heard anyone say they ran out and the gauge wasn't flashing!!

Driving a Prius with no fuel in it can void the drive train warranty. Always call for help and don't drive on the battery after running out of fuel. Better still, never run out of fuel.

 

This is true. But it can stay at ten bars for days, and then suddenly jump from three bars to one in a minute.

 

Sorry I am not familiar with that behavour. Australian Prius don't have a bladder.
Oh, we have a height adjustable seat though!!

 

Sure, go ahead, rub it in! Bloody Aussies :_> (BTW, is "pom" a bad word?)

 

I always find this to be such an interesting sociological question. Why is it that people with Prii seem to believe the computer display and the presumption of 11.9 gallons before they will believe the flashing last pip and the car telling them to "add fuel" on the MFD?

When the car asks for gas, just feed it. THere is no reason to get more miles out of a bladder-full of gas. Filling the tank does NOT change the fuel economy.

 

I think you are delving too deep into the question as to how people regard a fuel gauge that is on or close to empty.

Many cars are designed to go 50 or perhaps many more miles when the gauge indicates empty until fuel exhaustion. People procrastinate, they wait too long; it's just a fact of life. If you were to design a fuel gauge that would only indicate empty when indeed there is no fuel left in the tank, I guarantee you would see many more cars stranded on the side of the road. Your typical driver is not a highly trained airline or military pilot, most likely just your average Joe going from here to there. When I was flying professionally, fuel remaining and distance to go to our destination were calculated every few minutes in the flight.

The Prius is different from other autos in that some report running out of fuel very soon after 3 bars are indicated or others report going 50 or more miles on a flashing pip. Unlike modern civilian commercial or military aircraft that have extremely accurate fuel gauges, the Prius's fuel gauge is so inaccurate it borders on the absurd. It has frequently been referred to on this board as the 'guess gauge'.

A quick look through past numerous postings on this board have documented this fact along with the peculiarities of the fuel bladder, the severe and very costly damage which may occur if the tank is simply topped off, refueling on a slope (which requires a reset of the fuel gauge system), and of course the fuel gauge itself.

As always, the threads always end with 'there's nothing you can do, just live with it'.

Rick
#4 2006

 

I think I read the fuel capacity is 5 liters less at 0 degrees than 70? Thats a lot. The other thing is some people look at their cruising range like their mpg... it becomes a game for them to see how high they can get their mpg... and also their cruising range, therefore they run it a lot longer into the danger zone of running empty.

 

1- What happens by "topping off" the fuel tank? I have read that letting it run out of fuel is a problem, but not topping it off.
2- How do you reset the fuel gauge? Maybe thats why there are reports of people running out of fuel at 3 bars.

 

1. Topping off can saturate the vapor recovery system and other components. There's a thread about the expensive possible consequences of this and a pointer to an external site cautioning against it (neither of which I have at hand at the moment). And even if no damage occurs it greatly increases hydrocarbon emissions from the car, which counters one of the reasons for buying a Prius in the first place.
2. Re-fueling with the car more-or-less level will reset it. Until you do that the previous off-level refueling may give an inaccurate reading.