Fuel Gauge is too conservative?

**disclaimer**

the following post should not be construed in any way as a recommendation of any sort. your circumstances are unique and thus everything below should be used for informational purposes and not as a guideline in any way

**end of disclaimer**

CANVIEW has shown in previous models that the last bar starts to blink when the tank is at 12% full which means there is at least 1.5 gallons of fuel left. this is standard Toyota practice and has been so for DECADES. every Toyota i have ever owned had a fuel light (not counting my 1970 Corona. it may have but i dont remember it) that came on halfway between ¼ and empty which is an eighth which is 12.5%....

so when u get to the change from 2 pips to one, you are probably near 2 gallons remaining.

now you can use any guideline you want, but one i look at is that the tank gauge is probably set at an inverted bell curve. so, i note the mileage at which the first bar DISAPPEARS...or the transition from 10 pips to 9.... i consider this to be my safe zone and that happens between 80 to 120 miles.

now, i know my tank is not full to the tippy top, since i dont top off and the bottom of the tank is full to the ahh...well "tippy bottom", so driving the same distance after the blinking bar is safe as the distance i lost the first bar.

once again, this is not recommended, do what you are comfortable with and remember if you are grousing about getting only 9 gallons in the tank after driving 500 miles, remember last week, last month or last year, whatever the case maybe when you drove 450 miles and put 15 gallons in the tank

**edit**

didnt mean to post, but my Son was in the room... but anyway, ran out to the car... have been on blinking bar since last Friday.

DTE is zero... probably has been for a while. only have about 60 miles or so since bar started blinking, so probably have another week or so....

 

if i were doing what you are doing, i would push the envelop more since i dont drive that much and do anyway. i generally dont even consider getting gas until i am at least 50 miles into the blinking pip.

having had CANVIEW on my 2004 tidelands where it measured tank capacity in 2.5 % increments gave me a lot more confidence to push the tank.

now this site comes up with one of those "i had two bars and ran out of gas" or "ran out of gas less than 5 miles after last pip started blinking" etc...

personally, i think its user error or a mechanical failure of some sort (unlikely since it disappears as soon as gas is added to the equation)
but who knows??

but i just put gas in the SPM today. last fillup was june 23rd. but she doesnt drive that much.

probably put gas in the 2010 sometime this week. last filled it July 2nd (but did drive 350 miles in one day on Leavenworth trip) so we dont drive much...

so the inconvenience of filling up is pretty much a non-issue. it all boils down to knowing your car.

dont run the car thinking you have an 12 gallon tank. that is only the case if you filled it to the very top. if you dont like putting in 9 gallons and would rather put in 10 or 10.5 (wouldnt go more than that) then drive 10 gallons worth. if you are averaging 50 mpg. dont fill up until you hit 500 miles.

 

Flying airplanes, I like to know how much gas remains in the tank for every flight. I would like to know that in the Prius. I filled up the other day with 47 miles to empty and it took 9.1 gallons. A full 20% of fuel remained in the tank. Next time I'm going to take it to zero or as close as I can to see if that takes it down to 1.9 gallons. I'll do that again to see how accurate it is. I would like to know what is usable in the tank. Is that in the operator's manual?

 

LOL! xD

 

check my post in related thread #11

http://priuschat.com/forums/gen-iii...ate-your-distance-empty-gauge.html#post911499

 

Is this proportionately any worse than other makes and models of cars that PC members have owned?

While I'd love more precision in fuel gauging, this is no worse than the Honda that my Prius replaced, nor worse than a prior Ford. And is much better than the Subaru I still have. When the later's needle is squarely on 'E', it has well over 1/4 tank remaining.

 

+1 for that... On every other car I've owned, "E" was just the beginning of thinking about filling up. On analogue gauge cars, it was always some little dimple or rivet well below "E" that actually made me think about stopping. On the stupid Lincoln I'm trading for my IV on Monday (didn't qualify for clunkering, darn it), I've gone at least 50mi past the point when it's digital computer thingy predicted 0mi DTE. So I agree that greater accuracy would be nice, but I'm realistic about it.

 

That is true of almost every car I've owned. My first Ford, before the first fillup, actually ran out of fuel above 'E'.

 

So......was the bladder a good idea afterall? I would think the engine can suck gas from a bladder on a slope?

 

OMG, I'm so glad that this thread is here. I've had my Prius V for 3.5 weeks now and today I filled it up for the third time. The first tank registered at 575 miles to fill-up. I drove it until I had 2 bars left and the miles to fill-up meter said 100 miles. I figured I would be able to get about 10 gallons into the tank, since it's supposed to be a 12 gallon tank.....I only got 7.9 gallons in and it registered as 498 miles to fill-up. I was perplexed. I drove it for about 60 miles and then went back to the station, and it let me put in another 2.5 gallons.....very interesting, though it didn't raise the miles to fill-up past 513. Next fill-up was the same. Today, I filled-up with 2 bars (had been on two bars for at least 50 miles, so I figured it was 1.5 bars....and the miles to fill-up indicator said 65 miles. Since I am not yet used to the gas tank and how to estimate what I have left.....I filled-up. I should have been about to put in 10-11 gallons.....it let me put in a little over 8 gallons, and then the miles to fill-up only went to 510. What the heck is up with the tank? If I'm near empty, I should be able to put in 10 or 11 gallons, and I haven't come close. My 2007 TCH was easy to ready....when the meter went down to just above empty, I could put in 15+ gallons....for a 17 gallon tank. The miles to empty would go as high as 510 and was pretty accurate. The Prius V meters (don't know if it's because they are digital or what) are ridiculus and I don't know what to make of it.....I shouldn't have to worry that I'm going to run out of gas at 1/4 tank. Is there a fix for this....is there maybe air in my tank?

 

If you count 100 miles remaining, then it sounds like a lot of gas still sitting in the tank when that Empty light flashes. But if you count how many gallons are actually left in the tank, which is around 2, then it is perfectly normal.

It is industry standard to have 1 to 2 gallons on reserve in the tank when the fuel gauge shows Empty. You really shouldn't try to drive your car down to the last few drops of gas before you go to the gas station. Most cars need those 1 to 2 gallons to keep the fuel pump cool. Trying to use that last $5 of gas in the tank may cause you $200 in fuel pump damage later.

Also, the 2 gallons are needed to accommodate for ground inclines and other mechanical and environmental variables. Your car may never get to use the full 2 gallons to run the engine.

Just because you can 'normally' drive 50 miles with a gallon of gas under ideal condition doesn't mean ALL Prius drivers can too. A Prius with low tire pressure, bad road surface, severe weather, rush hour traffic, etc. will affect how many miles you will actually get before you run out of gas with those 2 last gallons. That 100 mile safety margin will quickly become much shorter if you are stuck in a winter blizzard with your heater running and going 2 miles an hour. You may be stuck on the road for 2 more hours before you can reach the next gas station. That 2 gallons reserve will seem like a good idea then. Since you are still getting 450 to 500 mile range on a normal tank fill up, there is no reason to complain or blame Toyota's engineers who has your car's reliability and your safety in mind to set that last 2 gallons on reserve in the tank.

If you really hate going to the gas station, just carry an extra 5 gallon portable fuel tank. Then you have a 750 miles range before your next trip to the gas station.

 

That sounds about right based on my last fill up. With 47 miles remaining, it took 9.1 gallons to fill it up. I think I will take mine down to zero next time. Our numbers should be the same.

 

some i have had have been much worse. case in point, my 1990 Ford F-150 which is sitting at my sister's house as we speak...

it had dual 18 gallon (might be 16 gallons?) tanks. first the switch to swap tanks broke...no biggie, this was when gas first hit $3 a gallon, other than 30 minutes to siphon the tank, no issues with that.

but the tank that it was stuck on, the gauge literally stopped working everytime it got below ¼ a tank. by not working, the gauge would literally swing from ½ to empty constantly depending on the movement of the truck.

i ran out of gas in this thing probably 5-6 times because i simply guessed bad on the tank or someone else used it and did not tell me or put gas in it.(the key for it sits in the ashtray 24/7 and 3 different households use it )

so, to be honest with ya, its all a question of common sense. now do i put gas in my Pri as soon as it tells me to?? well, you all know the question to that?

and i do not have an overwhelming urge to get "get value" out of my roadside assistance either

 

I had a 1972 Jeep C-J5 with a fuel gauge that worked normally down to about a quarter of a tank, at which point the indicator jumped to full. I ran that one out of gas a couple of times when I wasn't paying close attention.

Tom

 

either you "know" its there or you dont. make up your mind.

what i would do if i were you, as soon as the last bar starts to blink, reset Trip B and drive 100 miles and then start thinking about getting gas.

this will lessen your frustration. now what it does to your anxiety level; well, that quite frankly, is up to you

 

My first tank was filled by the dealer on friday and I just got to the 1 pip mark tonight. I put in 9 gallons (two clicks) and calculated mpg was 51.5 compared to 55.1 on the MID. Not bad, especially since I don't know exactly how much gas the dealer put in. I should get more precise calculated MPG this time around and I'll report back.

 

I think owner's manual stated Prius III needs 1.5 Gal to start the system, so I guess it is not a good idea to go below 2 Gal at all.

I can confirm with one solid bar left, I was able to put in 9.5 Gal of gas.