"Gas bladder, this isn't normal"

After you filled six gallons, what does the fuel gauge read?

How many times do you have the pump click off, before you stop pumping?

 

6 gallons would be just about right for that fillup. 320 miles @ 56MPG = 5.71 gallons used. At 2 pips you might have had as much as 1.5 to 2 gallons left in the tank.

 

Sounds about right to me. I filled up this morning with three pips showing because gas was down to $3.12 per gal. I had traveled 320 miles since the last fill-up and put in 6.5 gal.

Car showed 47.1 mpg and the fill-up calculated to 49.3 actual mpg. The most common number of gallons on my spread sheet is 7.** and I usually fill-up at two or three pips. I always stop filling at the first click.

 

There's probably two gallons of "headroom" left if you stop after the first click. So, if your goal is to maximize the range on a tank of gas, then you can squeeze in at least another gallon after the first click.

However, you are taking some risk that you may eventually damage the evaporative emissions controls on top of the fuel tank.

 

You could try. A few owners appear to have been unpleasantly surprised by an out-of-gas situation before reaching one pip.

It seems that the guess gauge is quite variable. Hence the amount of fuel that actually exists at a given bar reading is not well-defined.

 

You really should try reading some of those 5000 threads. This is THE most common fuel system-related complaint. I had the same problem; could not refill the tank with more than 7.5 gallons for over six months. Find my post in the following thread. It may or may not help you but you should get some new insight into the problem.

http://priuschat.com/forums/fuel-economy/52456-my-first-60mpg-tank-also-my-first-700-mile-tank.html

 

If you're complaining about the range, fill after the first click. Usually you can safely put in another gallon. It's because the fuel foams a bit during filling, and that foam tricks the nossle into shutting off early. I get another 100 km (60 mi) by doing that.

You only have to worry about an overfill if you can see fuel in the filler tube. It takes a lot of extra clicks of the nossle to get up that far, unless you are filling at the slowest setting.

 

Just stop when the pump clicks off, take your 6 or 7 gallons, and get on with your life. Why is it such a big deal?

 

Regarding runing out of fuel, When you get down to the last bar on the fuel gage you have at least three gallons left in the tank. I have found that once the last bar starts to flash I have at least 50 miles left before the "add fuel message" comes on. Then you have quite a few miles before you get the "add fuel soon" message. I have a very long commute to work and get 500 miles every week out of a tank, and have gone 575 miles on a tank. I have never heard of damage to any systems by filling the tank all the way and fill the tank weekly full - after the pump clicks off I usually put one to two gallons in. I have been doing this for three and a half years with no problems.

 

I'm sorry you're not seeing any improvement. The "insight" to which I was referring was that the conventional wisdom did not work for me either. Pumping slowly did no good. So I started experimenting with UNconventional methods. I DO think that the crucial issue is the ambient temp as it affects the ability of the bladder to expand. Unfortunately, the weather is turning cooler now. I am seeing indications that my tank capacity is reducing slowly already.

There are a number of methods to try, many have already been suggested. You may need to consider several in combination. Be creative.
For a (wild) example, if you have a heated garage, (to warm up the bladder) perhaps filling from gas cans in the garage might help. (?)

The real hypermilers go to interesting extremes. Examples: (1)Pump until full, then rock the car several times. Pump again. (2)Place a short 2x4 in front of the left rear tire and drive onto it before pumping. (3)Pump until full, ride a mile or two, return to the station, pump again. (I've used that one occasionally for an additional two gallons.)

One of my questions has been "What is overfilling?" David Beale's answer is best: When you see fuel in the top of the filler tube. But, (as I've said before) I think the fuel system is more robust than most PC'ers believe, based on the number of warnings about overfilling I've read. There are two valves in the system which work to prevent damage when attempting to overfill. These valves can still be defeated, however. According to the Toyota document I read, not fully inserting the nozzle into the filler tube when pumping causes the greatest risk of damage. Take that for what it's worth.

 

I had the pleasure of running out of gas once. When I limped to a station on electric only, my Prius took only 10 gallons! I have since discovered that this is the norm. The only way to completely top up is to continue squeezing off dribs and drabs until it REALLY tops up. When totally full, I can go around 180 miles before the first blip on the guage goes out.

 

nooaah, as they say on The Price is Right, "Lower. Lower." Are you tracking your fuel economy? If not, start. Normally you can refuel with 1 solid pip without worry. When the last pip flashes it is literally anyone's guess how long the car will run before running out of gas. Given your numbers you should be OK going down to 1 pip. I suspect your "problem" is your terrain. Many here do not know of the steep grades in your neighborhood. Whenever a car is not level the gas sloshes to one end of the tank which will either raise or lower the float causing wild readings. A right turn would add 1/8 tank (indicated) on my '75 LeMans.

If you take the Prius to the dealer they will put it on a level surface and will find the fuel sensors check out.

 

You need to drive it down to the low fuel warning, which is 1 pip blinking.
Go fill up, and after the first shut-off, you should be able to pump about a gallon more with no issues.
10 gallons should be a min usable quantity in any prius tank. More when you get familiar with you car.

If I filled up at 2 pips, I'd be depriving myself of 1/4 of this cars range, fuel capacity, and usability. Accepting 6 gallon fillups is non-sense and unnecessary for a Prius or any car.