New Prius - Strange Gas Tank

The tank has a bladder in it. In cold weather it becomes stiffer and you can't get as much gas into the tank.

 

There's a lot of discussion here on PC about the tank and filling. Check out this thread...
http://priuschat.com/forums/knowled...gas-tank-filling-up-issues-12.html#post761785

I try to fill at half tank empty approx. 200+ miles, "burp" the tank several times before filling (open the rubber guard around the gas inlet) and pump very slowly.
It's great that this is our major complaint. Also note the grill blocking discussions. A six foot strand of half inch insulation foam is less than $2.00 at Lowes and is very easy to fit into the grill.
Good luck and enjoy the savings !

 

Rick,

For the record, I've had no problems refilling my car, except for the first time when I was doing it wrong. Our temps never get below 40 F, don't know about temp factor.

Not saying you're doing the stuff below, just offering suggestions -

Do not stuff the fuel nozzle too far into the filler neck. I just put it in a bit with the handle tilted down so the nozzle is tilted up in the filler neck.

Look at your gas pump. It may show a diagram of how to position the nozzle in the filler neck.

Once I set it in place, I just put it on the lowest 'latch' setting. I've been able to get all 10 pips for 4 or 5 fillups staight.

I only had trouble on the first fillup as I was stuffing the nozzle way down into the filler neck. Prius does not like that.

I don't try to get a tight seal of the rubber ring around the fuel nozzle. I just want the tank to refill. Once it clicks off, I'm done. Don't want gas spitting back out at me.

Hope that helps.

 

There are several things at play:

1. The coefficient of thermal expansion for plastic/polymers is greater than for many other materials. As a result the tank bladder shrinks appreciably during cold weather. Toyota even warns of this in the manual. The colder it gets the more shrinkage. The effect is not huge, but it is enough to notice when it gets cold, particularly as far north as Minnesota. You can easily lose over a gallon of capacity this way.

2. Another problem is the bladder might "stick" and not quite expand as it should. This problem is likely to be more prevalent in cold weather. Plastics get stiffer as mercury plummets.

3. There are many potential problems with the overly complex vent/vapor system in this bladder tank.

Personally, I think half tank fills are counterproductive in cold weather because you've already effectively lost about a gallon of capacity on what is a small capacity tank. Plus, I don't like a lot of extra trips to the gas pump standing around waiting on tiny fills in the cold and the wind cutting through like a knife.

But regardless of what I or anyone else thinks you will have to experiment a little to find out what works best for your tank.

 

Cold bladder issue. I would fill the tank as usual, then when the pump shuts off, wait a minute to allow the bladder warm and expand. Then fill again. Repeat this as much as you like but do not overfill out the neck or you'll ask for more problems than it's worth.

 

I got over 10 gallons in last night, a first! I couldn't believe it and had to scratch my eyes when looking at the read out.

even during the summer months I only get about 9 or 9.5 gallons MAX

this was 10.7 after driving on blinking pip for 60 extra miles/ Temps around 38 degree's when I filled up.

the bladder sucks, but you will get used to it..nothing you can do really unless you can find someone to fit a regular tank re program the electronics, voiding your warranty.

 

I fill slowly (lowest auto-click setting) and stop when the pump clicks off. My Prius typically takes seven to eight gallons when filling from one to two pips on the gas gauge. This is true even with our current 10°F weather.

Tom

 

Hi Rick,

The Prius fuel tank bladder capacity can decrease one or two gallons due to severe ambient temp decreases. Further, there's also variability in the way that gas pump nozzles respond and shut off. Perhaps if you try a different pump you will have a more satisfying outcome regarding filling your tank more than halfway. Experiment a little and see what works for your car. Good luck.

 

I too filled up last night. Ambient temp was just above 0F (it was -15C). I just put in the nossle and fire away full throttle. When it clicks off I pull the nossle out so I can see what's happening and to relieve any pressure buildup. I then pump in fuel until it begins to bubble to the filler tube top. Then I pump in small amounts until it bubbles to the filler tube top after a second or so. At that point I stop. No fuel is visible in the filler tube (a "good thing" (tm). Search for overfilling. Last night it took Pearl about 5 min before she lit up the last pip on the guess gauge.
Best part was the fuel cost $0.64/litre! A $14 fillup for 20 l (about 1/2 tank)! It was up to $1.40 or so last summer. I knew our temps are going to tank again back down to the -30C range, so I wanted to fill up when it was "warm".

I suspect you had a bad or inconsistant pump nossle.

 

I always refill at 2 pips/300+ miles and I always get 6 gallons at the first click. Should I be safe to try to go an extra 50 miles and see if it then fills 7 gallons? Or when I go for my free 5,000 mile oil change, should I ask the dealership to reset the sensor?