2004 Prius Fuel Indicator

[remonical]

When the last bar on my fuel guage starts blinking, I can only put about 8.5 to 9.0 gallons in the tank before the gas pump shuts off. The manual advises to not put any more in the tank due to possible damage of parts inside the tank. Also, the pump just shuts off again with very little additional gas transfered . The amount of gas is way short of the quoted tank capacity of 11.9 gallons. I don't want to go past the blinking bar on the indicator for fear of running out of gas (even though I know I have some miles left from the power battery). Does anyone know how the guage is calibrated, i.e., how much is left when the blinking starts?

,

Dick Monical

[vincent]

I rented an 05 Prius for 4 months while my 06 was on order. At my first fill up for the 05, I put in 2 gallons after the pump clicked off. Literally, gas was coming out of the tank and I stopped. I went 180 miles on that tank before the the first light on the gas gauge went out.

Now that I know better, I only put in one gallon after the pump clicks off, but there's room for more (you have to take the pump handle almost out of the tank to add the extra gallon). Today, with the gas gauge just starting to flash, the pump clicked off at 8.6 gallons; I added another gallon for the 505 mile refill, for a total 52.6 MPG. For me, the effective capacity is around 10 gallons; God only knows where the other 1.9 gallons goes??

I understand the capacity is reduced in cold weather areas when the gas tank bladder can't expand as much.

[remonical]

Thanks for the response, Vincent! I don't seem to be able to get "hardly" any more fuel in the tank after the pump shuts off. It's almost as if there is a false fuel level up next to the lip of the tube because the fuel level seems to be lower. I have a 2002 Prius in addition to my 2004 and it does not exhibit this feature. I feel kind of cheated with only 8 or so gallons of useable fuel. Either the unused space is at the top of the tank or the bottom of the tank and the guage is just not up to Toyota standards! Maybe someone will see our posts and shed some light!

[vincent]

There is lots of information on the fuel tank capacity problem over at Priuschat.com, if you have the patience to search through the posts.

The basic problem seems to stem from the flexible bladder inside the fuel tank. The bladder is there to help capture escaping fuel emissions; that's the good news. The bad news is when it's new, or cold, or just gets cranky, it doesn't fully expand to allow a full 11.9 gallon fillup; is it still cold in Kansas? Well, it's almost always hot here and my Prius is now 4 months old and I can never get full fillup; souhds like a design flaw.

If you pump slowly after the the handle clicks off with the nozzle almost completely out of the filler neck, you can pump more gas in (I've gotten in as much as 2 gallons on the rental Prius; it's called a "superfill"). BE CAREFUL, if you "superfill" you will force some liquid fuel into the charcoal emissions filter, which was only designed to hold vapors. I understand a build up of liquid fuel in the filter will negatively effect MPG's as well as kill your zero emissions rating.

[remonical]

So that's why they don't want you to "superfil" the tank! Having the reason is a whole lot better than "don't do it!" I guess I'll just be satisfied with a 9 gallon tank.

It has been pretty hot since the cold months, but the past few days have been cool. It was 55 degrees this afternoon, which is pretty cool for this time of year.

Thanks again for the help!

[budput]

By going to a rundown gas station with a faulty pump nozzle I managed to put 12.9 gal (less a quart or so on the ground) in my tank which I feel sure had at least 2 gal in it to start. I then went about 225 miles before the gauge came down to nine squares. I don't recommend this. It is part of a long tale which began when my 12V battery went flat after 3 weeks of inactivity.(I have another post on the flat battery caper.) To make a long story short, AAA jump started me and added gas which I was surprised I needed. I had parked on a cold day and tried to start up on a hot one. AAA followed me to a Toyota dealership which treated me royally: they redid the "inclination" adjustment, which affects the gauge, and washed the car, for a net charge of $0.00. I have started to top up at a good gas station, and refill after about 400 miles (~8 gal). Average mpg on the screen
agrees well with miles travelled and amount necessary to top up tank. I don't think fuelling every 400 miles is a great burden. T. say that running out of gas is bad for the car, but I don't know whether to believe that.

[e.matez]

I just got an 07 Prius a few weeks ago The 1st time the blinking gas light went on and I filled up immediately only to put in 8 gallons I checked the manual and it said it is a 11.9 gallon tank The second time I waited a little longer to fill up and put in 8+ gallons but nowhere near the professed 11.9 This past weekend, I nearly ran out of gas (the car had started to lurch a bit.) Fortunately I was near a gas station When I filled up, the car only took 9.1 gallons... Thanks to the discussion at this forum, I realize the reason Toyota dealers should really explain this better to their customers. They definitely are asleep at the wheel on this