But the key here is we don't know what "overfilling" means in the context of the Prius.

We have an 11.9 gallon fuel capacity (if Toyota's spec is correct), yet we have innumerable reports that the gauge implies "empty" when one can only pump 7-8 gallons in before pump shut-off.

In my experience, gas station pumps are highly variable as to when cutoff occurs. I have been making it a standard practice to drive about 1.5 gallons past the "add fuel" warning. Depending on the pump, cutoff on refills occurs at 5.6gal to 8gal. In all cases, the fill can continue up to 10 gallons without any trace of overfill (no gurgling in filler tube, no flashback on removal of nozzle).

Something doesn't jive. I think one factor is the back-pressure from the bladder (plus the sealed filler tube) causes pumps to cut off far earlier than they would on conventional tanks.

Bob.

 

Jack --

Great reply. What we really need is the actual data, and design of the fuel delivery and input system. As a chemist, I always want people to "show me the reference", or the original data. It sounds like you have experience in this area -- do you know where we could get real data or design specifications?

The only thing I found in the owner's manual is that the bladder will shrink in cold temps, but the data cited there (I think maximum 1.1 gal at some negative farenheit) is not enough to explain everyone's problems.

I just picked up my Seaside Pearl #9 (still thinking of a name) on Saturday, so haven't filled up yet. It will be interesting to see how my car does in relation to everyone else's.

Jeanne

 

Well, just filled the tank. Auto shutoff at 7.5 gallons, and I was able to add 2 more gallons into the tank afterward by letting it sit for a minute while I checked the oil, then pumping very slowly. 150 miles later, my gas gauge is still at 10 bars!

We'll see what happens, but I'm concurring with the early shutoff crowd right now.

 

Yeah, I think I'll be topping off a bit more now. I fell 1 bar down after 60 miles.

 

Mmm... my car has a tank that holds over 18 gallons...

 

Aloha,

I live in Honolulu. It is normally 75-83 degrees currently this time of the year. I have filled my tank up twice the first time I travelled 418 miles and put 8.6 gallons into the tank (48.6 mpg/ 52.9 indicated on screen). The second tank I travelled 485 miles and put 9.2 gallons into the tank (52.7 mpg / 52.8 indicated on screen) Neither time was the last bar "BLINKING". On the second tank I travelled 10 miles on the last bar and decided to gas it. Will continue to keep track to see if amount of gas the tank increased s the bladder "wears in". Temperature should not be a factor here.

Bottom line is even if I fill it only with 9 gallons I am still travelling almost 500 miles on a tank!!!!

 

Hi Jeanne (Gee - my Dad is a dentist. Guess you know what is coming??

This is the best I have seen so far: Tank Schematic Diagram

The tank bladder was described by someone knowledgable on the Yahoo group as "more like a water bottle".

I remain somewhat dismayed that folks believe that the flashing light is indicative of a "nearly empty" tank and that squeezing in more gas after pump shutoff is a "good thing" - but whatever. I consistently run now over 500 miles on a tank - and whether the tank "really" holds 11.9 or 10.2 or 3 gallons is totally immaterial to me.

Its not the physics of the bladder that should concern anyone - it is the physics of the fuel return and vapour management system.

Jack

 

Your link is broken.

 

Again with the broken links?? Wierd - well - it works fine for me - but that may be because I am dragging it from my own login - maybe it needs to be "seperated"? Would you, Jason, like maybe to drag the image to your site and we can ref it there?

Not sure of another reasonable way to do it, really. For those of you on the Yahoo group for the 2004-Prius, it is in the Files section listed as "Fuel Tank Diagram.png"

Jack

 

Here's one that should work for everyone:
http://autos.groups.yahoo.com/group/2004-p...k%20diagram.png