Bladder Tank Frustration

The best advice I can give you on the bladder is the following. When refueling try this.

1. Before adding fuel loosen the cap at least half way and allow the system to vent for at least 60 seconds. Longer is better. If you are using a card as in your situation, then loosen the cap and check the oil and fluid levels before attempting to add fuel.
2. After the system has vented, remove the cap and insert the nozzle fully into the neck. Then start adding fuel. When doing so, use the auto fill on the pump and use the slowest setting on the nozzle.
3. When the nozzle clicks off, hang up the nozzle and replace the cap.

I also recommend that you refuel before you get to the last pip or the flashing pip. In cold climates the bladder is collapsed by then and sometimes will not unfold properly. That is why the bladder only accepts a small amount of fuel. This problem is also exacerbated by the speed of various pumps. Some pumps deliver more volume than others even at the slowest speed. It might help to try a different pump also when you experience the problem you did.

I would suggest you drive your Prius a minimum of 150 miles before attempting to add more fuel. Hopefully the next time the bladder will expand properly and allow you to refill it.

I cannot recall the exact reason why Toyota used the bladder on the Gen II, but I believe it has do with meeting certain requirements for certain certifications. I just can't remember what that cert is. The Gen III does not have the bladder.

Try venting the next time you refuel and make sure you use the slowest speed on the nozzle. FWIW, during the winter our Prius usually takes around 6 gallons to refill at 2 pips, but during the summer at 2 pips it will take seven to eight to refill.

You might want to update your profile to show your location. This will help others when responding to you as not all Prius will have certain parts due to location of manufacture and use thereof.

 

I could try to explain it...but a subconscious desire to embellish and entertain would probably have me add something about winged monkeys and lost treasure.

So instead Why does Prius gas tank have a bladder? - GreenHybrid - Hybrid Cars

 

Here is my experience. Weather: COLD
1. Depends on the gas station.
2. You control the fuel flow and just push lightlty and it will fill up.
3. Usually it fills up to 8 gallons.
4. 40-45 mpg

I have yet to see what it does in the summer.

 

The benefit of the flexible resin bladder, found in North American Classic and 2G Prius, is to reduce hydrocarbon emissions by reducing the space in which fuel can evaporate. That, along with the engine coolant heat recovery system, helps the North American 2G Prius qualify for AT-PZEV certification in California and other CARB states.

Owners in those states benefit from the certification because the hybrid systems and emissions warranty periods are extended substantially. Owners in non-CARB states benefit primarily by knowing their vehicles place less stress on the environment via lower hydrocarbons emissions.

If the gasoline pump nozzle does not tightly fit into the Prius fuel filler neck (which has a rubber seal around the opening) that will reduce the ultimate fuel tank capacity. This is why some owners notice that some pumps do not work very well to fill the Prius tank, as compared to others.

For more details, see:
http://www.autoshop101.com/forms/Hybrid13.pdf

 

That's my report to, the same for 6 winters here in Minnesota. It was consistent and never a problem. Pushing beyond 8 gallons (driving well after the refill warning triggers) is the source of complaints for many. They feel the need to add more gas is a reasonable expectation. I never understood why. My Taurus certainly couldn't ever drive a far as the Prius in winter between refills.

In the summer, I'd get an extra gallon of gas capacity. MPG would obviously go way up too.

As for the need for the bladder itself, I was always in full agreement about the benefit of reducing evaporative emissions. So, it was worth the loss of a gallon during the dead of winter.

 

Patrick is right on the bladder. Also the bladder can have another benefit - reducing condensation build in the bladder itself.

I, just use the lowest pour rate from the nozzle, especially in cold weather. Once the nozzle "clicks" off, STOP.
You do not want to try to over fill the bladder. In cold weather, with 2 - 3 bips on the gauge, anywhere from 4.5 - 8 gals will fill the tank.

In warmer weather, I can fill the tank at a faster rate.

Hopes this helps,

DBCassidy

 

But what about the winged monkeys and lost treasure? I'm sure Toyota employed the gas bladder to hide lost treasure and make the Prius fuel system invulnerable to winged monkey attack.

 

When the temps get warmer (summer) you will find that the bladder will hold more fuel. Hence your range will increase. You are experiencing the curse of the bladder. Hang in there, maybe the ground hog won't see his shadow this year. Summer will be here soon and with that will come more room for the push water.

 

This is for "The Electric Me".

 

I'm going to have to look into these things more. Opened this thread because I've got a car showing only 1 bar of fuel, but I dumped 4+ gallons in it with a jerry can and it still only reads 1 bar (despite fuel flowing out the filler neck when as if it were overfull-- which I just learned is bad for the charcoal canister and so on. Uh oh.

I'm an example of Ignorance is Bliss, but looking at the linked .pdf started to answer other questions I was trying to avoid asking myself...

I put an "alternative drivetrain" in a 2008 Prius mostly for comic effect, but somehow it worked so I 'ran with it'. I put an inline 2-4psi fuel pump mounted in the engine bay and sucking on the stock fuel line that exits up there. We did this because I'd figured out that there was a bladder-sealed tank but I'd didn't want to mess with putting a fuel cell in the hatch area. Sucking through the stock fuel system seemed to work pretty ok.

BUT I we noticed that we needed to keep the fuel level pretty high to avoid driveability issues. And at one point we experienced what we thought was fuel starvation due to a bad fuel pump. Swapping out the fuel pump helped, or so we thought. The points on the engine distributer also seemed to keep closing up, so we started to hypothesize the "fuel issues" we were experiencing were actually ignition timing related.

NOW I'm wondering if the complicated (for our needs) fuel system is what's causing the issues we are experiencing. The issues seem to grow the longer the vehicle is operated continuously. Since the fuel pump is supposed to be a pusher pump and not a puller pump, I knew we'd have some issues. Also, since were' sucking through the stock pump and whatever filter sock is in there, I recognized more potential for issues. But now learning that with a completely sealed system, I wonder if we're getting a vacuum in the bladder tank making it even more difficult for our pump to suck and deliver fuel to the front of the car. I did cap off the return line at the front of the engine bay, but perhaps I should leave this open to help provide a vent for the tank. Hmm. I need to read more.

 

"But now learning that with a completely sealed system, I wonder if we're getting a vacuum in the bladder tank making it even more difficult for our pump to suck and deliver fuel to the front of the car."
I am assuming that you have mounted a motorcycle engine and transmission in a Prius. I further assume that the fuel pump in the fuel tank is not powered up. That fuel pump would deliver 43 psi pressure.

I think it is reasonable that a vacuum is being developed which makes it difficult for the engine bay-mounted fuel pump. You could test that by leaving the fuel tank cap off, but that poses a safety issue, not to mention an emissions issue (although the latter may not be important to you since you've installed a motorcycle engine...)

 

Unless there is a one way, or fill check valve, I would say there is no vacuum in the tank. Reason: you are filling at atmospheric pressure. As the fuel pump draws fuel from the bladder, the bladder collapses, there is no vacuum in the bladder,as exterior air pressure creates this condition. When you do a fill up, the bladder expands, however, in cold temps, the expansion is likely to be impacted due to the bladder material becoming stiffer due to low temps.

When, temps moderate, or warm up the bladder material becomes more flexible, hence the expansion is increased. You will have an increase in the amount of gas that be dispenced into the bladder.

DBCassidy

 

thankful I have gen3 so no bladder. but could you take a small compressor and figure out a way to pump in some compressed air while sealing the filler neck to get the bladder to "pop" back out?

makes one almost think that putting in a cap that has a good vent or is slightly open and won't let the tank get into a "vaccum" situation would solve the collapsing bladder...

Yeah I guess that you might have an emission problem, and I guess the other question is whether or not running with a half open gas cap would trip off a CEL

 

"I guess the other question is whether or not running with a half open gas cap would trip off a CEL"
EKIM has installed a motorcycle drivetrain in a Prius body, so the only DTC that would be logged is whatever the motorcycle electronics will produce. Since EKIM refers to engine distributor points, I assume that the technology used here is ancient (dating back to the 1960's) and therefore there are no electronics, check engine light, or DTC to worry about.

 

Hi Guys,

Bought my Prius 2008 two weeks ago and still have a lot to learn. Have already experienced the bladder / refueling unpredictability - makes it very hard to calculate fuel milage - but haven't yet found anything comprehensive that explains the system.

By the (external) look of it, and reading comments here, it's a bladder inside a tank, and it's the bladder which contains the fuel. Initially, I thought it must be an air bladder inside the fuel tank which makes more sense to me, but maybe that's not it? Or maybe it is, and the bladder doesn't want to collapse to allow more fuel back into the tank?

So, my first question is, anyone know which way it is?

Then, how is the tank sealed or vented? If the tank is sealed (and the fuel is in the bladder), then air cannot get in to allow the bladder to shrink, or out to let it refill, and that's gonna be a problem. So, the tank must be vented, but where and how?

Anyone know where there's a good explanation for how it's designed and supposed to work?

 

Question arising...

If it's the bladder that holds the fuel, how the heck do they work out the Fuel Gauge level?

I could understand it, if it was an air bladder in a tank of fuel...