Inaccurate bar gas gage - anyone else experience it?

i didnt have the same problem on my first fill up, but it did take a little over 10 gallons of gas when the bar had just started flashing. it seems to me like you have to get to know your own gauge and hope that it doesnt fluctuate.

 

I've see many posters refer to it as a "guess gauge" instead of "gas gauge."

 

It is certainly inaccurate. I once drove 175 miles and still had 10 bars showing. I don't think it is a problem, however. I just fill it up when the last bar starts blinking. By the way, the car beeps to signal when the last bar starts to flash.

 

i don't mind, as long as you think about it then you'll be fine, its when you forget and you go 500 miles while you are only getting 40mpg, you might be in trouble.

 

I had the gas gage and filler tube fix many thousands of miles ago. I have never put in more than 9 gallons with the average still at around 8.2 gallons. I don't top off and don't want to risk running out so I generally fill-up within 30-40 miles of the last flashing bar. I sure do envy those that can put 11 gallons in and get 500+ miles per tank.

 

Do NOT trust the flashing light to show 2 gallons in the tank. I have gone 50 miles and run out of gas after the yellow light came on and I've gone 100 miles and still had some gas left in the tank.
Do NOT multiply mpg times gallons since the bladder in the tank may only allow 10 or 11 gallons to "fill" the tank.
When I picked up my 2004 I drove 150 miles on the freeway with no change on the gas gauge (I though it was broken and was about to turn around or call them).

 

it seems like everyone's "blinking bar" comes on at a different time. i filled up soon after it came on and got 10 gallons in there, but FredWB said that he only gets 8 or 9 in after going 50 miles after the blinking bar.

 

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Yes my gage is still a lot like yours. I think it improved somewhat after the "fix". But it still takes maybe 100 miles to go from 10 to 9. But at least it has not gone from 3 to one blinking withing a few miles like it did in the beginning. I just hate not really being able to use those 3-4 gallons with any confidence. Every car has some degree of trouble using that last gallon but there seems to be way too much variability with our cars and the only thing I got from the fix was a dashboard that sounds like the display is ready to fall off!

 

Hopefully the dealer did the Inclination Reset after doing the gauge/tube update. That is one thing to check if the gauge is off. I will post procedure later tonite,unless someone beats me to it, :lol: . Getting ready to leave for a meeting.

 

We just got our Prius and have encoutnered this as well. The First tank seemed ok, but after our first fillup, we went about 150 miles with it still saying full. Then in one day of driving about another 150 miles it went from 10 bars down to 3. When we filled it up at 2 bars we put 9.4 gallons in. Very disconcerting!

 

after driving 375 miles ,my gauge was exactly half full...
i went to fill and put in 7 gals...um...unless i stretched the bladder to hold 14 gals...this gauge is about as accurate as the gauge in the airplane wings...a big guess...unless you can put a broom stick in the tank and see how many inches are left...

 

its a little bit scary, especially if each car doesnt act the same way every time. i am hoping mine is at least consistent, even if its wrong.

 

remember most gas gauges are programmed this way...

the first half of the tank the gauge drops slowly. then the second half drops faster to compensate. carmakers do this to make it look like you're using less gas... even my 1990 Buick did that.

it's perfectly normal to go over 100 miles in your Pri and still have 10 bars. i hit 150 on this tank last night and still had 10 bars this morning. i drove about 40 miles today and i think i'm down to 8...

and of course our resident Prius Tech rick57 posted some helpful info about one of the few things that might be wrong with the car... if you run out of gas with 2 bars your inclination sensor may be off. this can happen if you fill the gas tank while parked at an incline. The gauge gets inaccurate and you can run out of gas with a few bars left, or may only be able to pump a gallon or 2 into the car. rick, you'll have to post the procedure, i just have the most recent hybrid system diagnosis training portfolio that describes the system...

but most issues are just quirks of the Prius... and you'll be fine if you just pay attention to the gas gauge like in any other car... happy driving 8)

 

i have also noticed a sort of delay in the gas gauge when on long continous driving trips. seems like the bars take a bit of time to disappear.

also, back when i was tracking how many miles each bar lasted, there would be times when i would park the car at night with 6 bars and come out the next morning and have 5... hard to believe that much evaporation can occur. this happened so often i gave up tracking the bars. but i did notice that this seemed to happen a lot if i had gone to issaquah, about 60 milers one way that it happened the most. so i figured that the gauge doesnt always update right away. kinda hard to believe since its all computerizd. makes me also think that maybe there is a weight sensor that determines the fullness of the bladder and it doesnt work as well when the car is moving.

who knows... just like any car ive had, just gotta learn the quirks of the system.

 

the less gas there is in the tank, the more room there is for vaporization... good point dave.

the gas gauge is actually a pipe that contains a float with a magnetic sensor. the changes in magnetic field due to height of the float are relayed to the meter ECU and then to the dash.

it's probably more complex than that, but i'm no car expert. i'm just citing the hybrid diagnosis book my husband borrowed from a prius tech at work...

 

but the bladder eliminates teh airspace so that shouldnt be an issue.

 

it's meant to "minimize" vapor, not eliminate it. it will contract with a decrease in fuel volume, but there will still be some vapor. the only way to eliminate vapor completely is to provide no space at all for a liquid to vaporize.