Inaccurate bar gas gage - anyone else experience it?

We've never seen the blinking bar on the gas gauge on our 5 mo. old Prius, because we never let it go below 3 bars. Most of the time we fill it when it is half down (5 bars.) Ours seems very accurate and we are really pleased that we don't have to figure gas mileage on every fillup anymore. The "average" mpg on the display is always what we get when we do the numbers. Sure nice to tell people that our car averages 45 mpg. (or more) on every tank, not just on the "best" tank as we used to do with our Buick. We cruised around the state park here on battery, but with a/c on, and actually saw 62.4 on the display....of course that changed when we got out on the highway. We are very happy with 45 mpg using a/c!

 

The bladder is only part of the story. It does keep down the amount air space that can hold vapor. However, the PZEV designation means no evaporative emissions, and if you study the diagram of the fuel system and it's related pipes and valves, what little air there is does get scrubbed and does not escape the fuel system.

If you have any evaporative emissions at all, your system is malfunctioning.

 

<div class='quotetop'>QUOTE(galaxee\";p=\"105762)</div>

And I thought you were a Renaissance woman.

:lol:

 

IsrAmeri... ha! :lol:

Nah... I'm just plain science geek woman.

 

science geek women unite!

we should start our own webpage.

 

all right! what do you do, Tiffany?

 

well, i am going for my biology degree... i'd like to work for the CDC in atlanta, researching cures for current diseases like cancer or ebola or something like that. what about you?

 

i'm a PhD candidate in pharmacology. i am currently studying side effects of anesthesia for my thesis. i'd like to end up testing clinical drugs.

 

Science geek women,alright, :lol: . Ok by me!

As for the Inclination Sensors,there are 2 located in the Combination Meter. They measure side to side and front to back angle of the Prius.Taking those readings and from the gauge in the tank,the meter knows how many bars to show the driver of fuel in the tank.Who knows why but sometimes the sensors need reset.The procedure is not hard but not done right can make the reading off more.It sometimes takes a couple of tries to get it going in the right pattern of pushes(see below).So here goes;

1. Park on a very level surface, Ready Mode, make sure Odometer reading is showing,then power off.
2. Hold down the Odo/Trip button while going to IGN ON ( foot off brake,not in Ready Mode!).
3. Release/press the Odo/Trip button 3 times in 5 secs. Should be holding the button in at this point.
4. 1st gen: You will see a set of numbers at this point within 5 secs. Release then press Odo/Trip again till you see a "1" which is Reset has begun.When finished,the Odometer will return to normal and you can release the button and power down.
2nd gen: You will also see numbers,but 6 in a row.Release and press again and you will see a set of 5 numbers.After the 3rd digit shows "1", release the button and Odometer should be back to normal.Power down.

For those with TSB acsess, the 1st gen is TSB EL008-03 and for the 2nd gen it is with the fuel tube upate. TSB EL010-04,see page 6.
This may not fix what some are experiencing, but could be, :roll: .

 

[font=Comic Sans MS:507b559eb3]Thanks, Rick! More mysteries revealed.

I wish all these programming tips were collected in one document or at least one permanent thread in the KB.[/font:507b559eb3]

 

how do you guys figure out these programming sequences in the first place? is there some secret document that you have? isnt there a list of these somewhere on the site? called "easter egg" something something?

 

check out www.techinfo.toyota.com

 

Yes,I guess you could say it resets the sensors. Or more accurately the Meter ECU. There is a pendulum inside the sensor that has 2 magnets on it. This is suspended in a silicon solution. By doing the reset procedure,the ECU knows where zero longitude and latitude are. That is why you need to do it on a very level surface or the reset is not accurate.

 

I have had my prius around 2 weeks. So far the gas gauge and the mpg screen are the most frustrating items. I love the car but don't like the constant math i do in my head. Sometimes I turn off the computer just so I can enjoy the drive. But when I fill up and get between 43 and 51 mpg i am happy.

 

I'd be curious to know what kind of level sensor they put in the tank.

I've noticed that after I fill up, it takes a long time (like 20 seconds or more) for the fuel gauge to climb back up to show a full tank. I guess it must be using some kind of average over time to keep the gauge from fluctuating over time, but it sure does react much slower than any other car I've driven. On every other car I've had, the fuel guage arm would sweep up to full in about 5 seconds after filling up.

Last friday I put in 3.5 gallons to top off the tank because my wife was going to drive it out of town the next day. The fuel gauge had been sitting a 1 bar down from full and after the fill up, it stayed there. I drove a couple of miles to a store, during which the gauge never went up to full. After I came out of the store and started it up again, it finally showed a full tank.

 

well.. reread the post just before yours. dont think you will get a better answer than what Rick 57 has to say. after all, most of us may drive a Prius but only a few here like Rick, make a living fixing them

 

Damn, I swear I read through everything, but I didn't see that post. Although I admit I started skimming a bit once all that "science geek women" tangent occurred.

 

ahh no problemo... we all do it. and the fact that both posts are fairly close together, its possible if you were multi-tasking multiple windows like i do, i might not have been there

 

Yep, that gas gauge is mysterious all right. Last tank I went 180 miles before going to nine bars. "Woohooo!" I thought, "I'm on my way to a 700 mile tank!" NOT! Drove through the tank and had 587 miles at the flashing bar. Then it took 8.6 gallons... not even over 9!

Now this tank.... I made it 48 miles, down to nine bars, 89 miles, eight bars, 149 miles, seven bars. The only difference in driving was more no construction highway driving. Right now I'm at 358 miles and four bars. I'm waiting to see what happens after the next fill up!