[shabusen]

I was down to one bar and planning on filling up the next day in an area where I know the prices are cheaper. For peace-of-mind though, I decided to buy ~10L (2.6 gal) to get me through the day.

Strangely enough -- given the 45L tank size -- the fuel gauge remained at one bar. I'd expected it to at least move up to two or three bars.

Is this a common issue when running on the shy side of the fuel gauge?

shab

 

[Sanny]

Sad to say, the bars have little relation to actual number of gallons, or even percent of tank. I can travel about 400 miles per tank. Frequently at 300 miles, I'm only just below half. Go figure! You might be better off figuring out how many gallons you do on an average tank, and then go buy some when you're nearing the end.

 

[Tideland Prius]

The fuel gauge won't move unless you pump more than 10 or 11 litres of fuel

Edit: This is from the manual pg 114

When you refuel less than about 11.4 L
(3.0 gal., 2.5 lmp. gal.), the fuel indicator
may not change.

 

[shabusen]

...This is from the manual pg 114...

Oops, that should have been my first reference point.

Thank you Sanny and Tideland for your prompt responses!

shab

 

[drash]

That's OK. Try explaining to your wife how much gas is left when she's spent the better part of her life dealing with 1/4s. The typical conversation goes like this with 2 bars showing:

W: "How much gas is left?"

Me: "20%."

W: "How much is 20%?"

Me: "1/5 of a tank."

W: "Which is?"

Me: "Less than a 1/4 of a tank." (and of course noting the quizzical look on her face I usually add) "around 2 gallons above reserve."

W: "Shouldn't we fill up?"

Me: "Why? I've never been able to put more than 9.8 gallons in before even during a flashing last bar."

W: "I still think we should fill up."

Me (at this point I'll shorten the conversation by just converting it to miles left based on number of miles we went on the tank and the MPG shown): "We have another 100 miles before we need to look for a gas station."

Which brings me to 2 major gripes. Why in heaven's name didn't the Toy engineers put in miles to go on a tank? My Avalon has it on that computer. Also why can't we just go metric like the rest of the world? As an engineer I wonder if those yahoos in Washington realize how expensive it is using our valuable time to do conversions and/or writing programs to do the conversions. They're dooming us to non-competitiveness because of all our time spent on arcane crap like conversions. Sorry just spouting off as I'm looking to another Monday.

 

[Tideland Prius]

Our bladder will probably make that reading unreliable. I noticed that the fuel gauge bars don't show absolute but relative fuel remaining so that when the bladder shrinks, it'll still be as 'accurate' as possible. IOW, half a tank in the summer will not be half a tank in the winter according to that gauge but half a tank of whatever the size of the tank is with that bladder.

 

[DanMan32]

Why no MTE? Well, as mentioned by Tideland, end of tank in gallons varies too much.

The other variable that varies too much is MPG, which is the other parameter needed in the equation Miles=Gallons* Miles/Gallon.

I suppose if you don't mind the MTE jumping around from 20-100, I suppose it could be added, but might not be meaningful.

 

[attila]

Indeed. This was one of the reasons why we wanted a MiniScanner. As I have a self-made onboard computer, it gives me both Estimated Remaining Mileage for fuel left for both "historical" and "trip" average. This was quite an adventure, as even the CAN reading ( the internal information highway on which the computer nodes communicate in the Prius ) is sporadic. I now have a "learning" system and one of the adjusted parameters is that when CAN reports '0', there is still about a gallon left in average.

The built-in fuelgage ('guessgauge') has an extra "feature", that it is showing everything "worst case". Basically if the CAN value ( sensor input ) goes down to 0 for a second and goes back again for 1/4 of a tank, the gage will urge you to fill up the tank, so you might have had over 3 gallons still available... This must be part of why you need to fill at least 10 liters or so, so that the program recognizes that it was not just an ordinary CAN value change, but indeed a fill-up.

It's a really tough problem, however, considering what an engineering marvel the Prius in general is, I agree that this should have been addressed better.

Attila

________

 

[ehurtley]

I was down to one bar and planning on filling up the next day in an area where I know the prices are cheaper. For peace-of-mind though, I decided to buy ~10L (2.6 gal) to get me through the day.

Strangely enough -- given the 45L tank size -- the fuel gauge remained at one bar. I'd expected it to at least move up to two or three bars.

Is this a common issue when running on the shy side of the fuel gauge?

shab

This weekend, I dropped down to a blinking bar, drove about 20 miles on that, then added 2 gal; it stayed blinking until I did a full fillup 50 miles later. (First time I've ever gone 70 miles on the blinking bar alone.) Again, because of the size of the tank, you'd think it would have AT LEAST stopped blinking. But it stayed there blinking away until I did a full fill.

 

[DanMan32]

It stayed blinking because you need at least 2.5-3 gallons for the meter to register increase in fuel.

This would be a good way for friends to play a trick on you. Every night they add 1 or 2 gallons. You'd never sense it, and you'd calculate 100MPG, even though the MFD shows 50.

 

[ehurtley]

It stayed blinking because you need at least 2.5-3 gallons for the meter to register increase in fuel.

This would be a good way for friends to play a trick on you. Every night they add 1 or 2 gallons. You'd never sense it, and you'd calculate 100MPG, even though the MFD shows 50.

Or, even better, add 2 gallons a day for a few days, until you're only 3 gallons short of really being full. Then, when your trip odo says 500+ miles, pull into the gas station 'filler up'. When you only pump 3 in, and they go "is that all?" Say 'Yeah, I only drove 500 miles this week.'

 

[evander]

A question regarding the final bar on fuel gauge. Everyone refers to their final "blinking" bar. This tank I decided to let it fall down to the final bar before filling up, just to see this "blinking". Alas, only the white bar. Will it flash eventually, or shall I just fill up and not take any chances? The manual indicates that flashing bar means "get thee to a station." My husband is driving off somewhere. Hope there's no horror story when he returns.

 

[Sanny]

...My husband is driving off somewhere. Hope there's no horror story when he returns.

At least it won't cost him much to fill it for you.

 

[evander]

True Sanny, but will I ever see the blinking "blinking" bar? I'm sure my dear husband will have devised some way for me to repay him for spent gas money.

 

[Hep]

A question regarding the final bar on fuel gauge. Everyone refers to their final "blinking" bar. This tank I decided to let it fall down to the final bar before filling up, just to see this "blinking". Alas, only the white bar. Will it flash eventually, or shall I just fill up and not take any chances? The manual indicates that flashing bar means "get thee to a station." My husband is driving off somewhere. Hope there's no horror story when he returns.

It will blink. Mine seems to be about 30 miles on the last bar before it beeps and starts blinking. It will give you a reminder beep on every start up until you fill it. I usually can only get in a tad over 8 gallons on the blinking bar, so I am not pushing my luck at all.

 

[evander]

Well, I guess I'll have to wait till next fillup to see a Prius blink. My husband filled up already. Said the tank took only 8.6 gallons with one non-blinking pip. I guess that means I had over a gallon left in. Thanks everyone.

 

[Astrowoman]

Yes, about 3.3 gallons if the tank really got filled!

 

[attila]

Fuel and related CAN value relations

I did some measurements on CAN values and fuel tank gallons.
I can run about 80 miles after the "Add Fuel" comes on...

http://www.vassfamily.net/ToyotaPrius/C ... index.html

Cheers,
Attila

 

[hyperion]

There is no excuse for running out of gas in an automobile. I can remember feeling sorry for the guy walking down the side of the road with a gas can. Now we "gamble" because we have a cell-phone and can call triple "A". The tow truck driver doesn't care about "the bar wasn't blinking yet."

 

[ehurtley]

There is no excuse for running out of gas in an automobile. I can remember feeling sorry for the guy walking down the side of the road with a gas can. Now we "gamble" because we have a cell-phone and can call triple "A". The tow truck driver doesn't care about "the bar wasn't blinking yet."

My first car had a completely screwy gas gauge. Some times it would be dead-on accurate, other times you'd run out of gas when it said you still had half a tank left. Miles driven was the only even vaguely accurate predictor. And then if someone else filled up, and forgot to reset the trip odometer, you'd have no clue. One time I ran out thinking I had an almost-full tank. (Someone else had done the last couple fillups, without resetting the trip odometer, so I saw 0045, and thought it was only 45 miles since the last fillup.)