111 miles on flashing pip

<div class='quotetop'>QUOTE(skguh @ Nov 8 2007, 03:07 PM) [snapback]536833[/snapback]</div>

I agree and I apologize. Rough day, and it was inappropriate for me to allow my emotions to affect what I type here.

<div class='quotetop'>QUOTE(skguh @ Nov 8 2007, 03:07 PM) [snapback]536833[/snapback]</div>

The point people have been trying to make is that such an answer doesn't exist.

The 'flashing pip' notification is not directly an indicator of gallons or miles. It is an indicator of the recent average height of the float in the tank. There are so many variables that can affect this, that it doesn't translate to a reliable concrete answer of specific gallons or miles.

The sensor in the tank is situated such that in nearly all typical situations (assuming nothing is broken), the 'flashing pip' will occur when the tank is neither full nor empty. I suspect that most people with knowledge or experience in the matter would be willing to suggest a range of more than 0.1 gallons and less than 5 gallons. Beyond that you might manage to get some guesses out of people or a slightly smaller range, but the fact remains that all you know is that the tank is neither still 'full' nor yet 'empty'.

If you fill immediately (or very soon) after you see the 'flashing pip' you will most likely never run out of gas. If you try to guess how much gas you have left in the tank, there is a strong likelihood that you will eventually be wrong.

 

Thank you. Accepted.

:some guesses out of people or a slightly smaller range, but the fact remains that all you know is that the tank is neither still 'full' nor yet 'empty'.

I suppose that I must accept it, but it runs counter-intuitive to everything else about the car. With the level of engineering mastered in putting this thing together, it seems almost less laughable to have a bobbing
cork inside a window to the tank! The simplicity of determining the contents of a fluid container, if the MPG calculator and the odometer are at all accurate, would seem easy enough.

Unless it's flashing, "Go EGG, Go." Flashing pip mean, "Whoa, EGG, Whoa." The extra (unknown) quantity of gas in the tank is merely a reserve for situations such as Pat Frank's 1959, "Alas, Babylon."

Okay, got it.

 

<div class='quotetop'>QUOTE(skguh @ Nov 9 2007, 08:45 AM) [snapback]537208[/snapback]</div>

Funny you should describe it that way. It is essentially a cork on the end of a pivoting stick. There are multiple electrical contacts that register the angle/height of the stick as it swivels. If you've ever watched a cup of coffee in your car while driving, you've got an idea of how the fuel might slosh around as you ascend or descend a hill, as you accelerate or decelerate, as you turn the carm etc.

Obviously the display on the dash doesn't occilate nearly as much. I'm not certain, but I assume the programming in the car must compute an average height/angle for the stick over some amount of time. Then it only registers decreases in that average unless the increase is significant (like the amount of height increase you'd get from about 3 gallons).

Here are some greate photographs of the Prius gas tank being disassembled, as well as some great photographs of the gauge that is inside the tank.

http://priuschat.com/index.php?showtopic=31545

Also, here is a great description of the entire Fuel/EVAP system with some great diagrams.

http://priuschat.com/index.php?act=Attach&...st&id=11954

 

It is, in fact, Rube Goldberg's gas gauge! OMG!! A cork bobber in a window WOULD be more accurate!

Thanks, Danny. I appreciate the patience. I can honestly say I've never seen a more complex gas tank. EVER. Looks like a case of over-analysing the problem!
Thanks again.
S

 

I think a big part of it is making certain that when you fill up you indeed have a full tank of gas. Most pumps turn off early and you can still fit another 2 gallons in at least. Just don't force the gas in because if you read through the forums there are people that have damaged their gas tanks.

I have run out of gas 2 times pushing the limits of the blinking light. The first time I went 230 miles and I was prepaired for it and had a gas can in the car with gas to get to the station.

The second time I went 175 miles expecting to get the same as the previous time. Luckily I was just down the street from the gas station and had plenty of power to get to the gas station.

I think this all differs from car to car but on mine I have found that once the light starts blinking I check my average gas mileage for the tank double it and that is the safe number I use before I run out of gas.

 

8.7 gallons on Flashing Pip

This is my first post here, and my first fill of my Prius tank. I put in 8.7 gallons with 446 miles on the ODO, and averaged 51 MPG in the past 200 miles (I reset the guage, apparently the 5 miles the dealership put on the car were at about 9 mpg or something)

So, assuming all the gas in the tank and bladder can be delivered to the engine, I could have driven another 150+ miles after the flashing PIP before I NEEDED gas.

It sounds to me like the PIP starts flashing at about the point where a regular analog fuel guage would be at about empty, and everyone knows you can drive quite a while with the guage pretty well below zero.