the gas bladder: exposed!

[Mr.Vanvandenburg]

I was thinking the same thing about the internal hoses, but saw the fuel tank is covered under the 15/150000 emissions defect warranty in CA states. I shouldn't have to worry how to put gas in my car. If mine gets this problem, it is going to the dealer. I only put gas in once so far and it showed full without any problems. I assume this occurs only with extreme cases of topping off. Anyway all cars have rubber hoses to the tank and they seem to last nearly forever.

[bwilson4web]

As I was adding a gallon to the tank from my spare gas can, I noticed the gurgling and realized that the bladder means we don't have gasoline saturated air coming from the tank. If every USA car had a bladder tank, we wouldn't need those dang 'fume traps' and seals that never seem to really work right.

Bob Wilson

[galaxee]

<div class='quotetop'>QUOTE(David Beale @ Apr 13 2007, 12:50 PM) [snapback]422724[/snapback]</div>

In my experience, even if you fill the canister with liquid fuel, it will still be fine once you remove the fuel. Usually they will clean themselves out by evaporation, though it will take time. The cars systems will not be "happy" (mil light and trouble code) while that is going on, if they can detect it.
[/b]

the prius has an exceptionally small charcoal canister. once inundated with fuel, it's ruined and it has to be replaced.

[bwilson4web]

Hi,

I wonder if you'll be reporting any more details about the small, white plastic pump-tank assembly?

The reason is I have been performing gasoline energy tests and have been running my NHW11 03 Prius tank dry, to engine fuel starvation. So far, I've gone, 130, 70 and 80 miles under the "blinking" low fuel indicator with an MFD display of ~55 MPG. This suggests there is about 1.4-1.5 gallons remaining after the low fuel indicator comes on. Knowing the capacity of the small, white tank might give some insights as to how that mechanism works.

In particular, I'd like to know if the the level of the bladder tank is the same as the white tank or is the fuel 'pumped' from the bladder into the white tank and then pumped to the injectors?

In aviation and motorcycles, we have a concept of a 'pony tank' or a small amount of fuel that is the absolute last in the system. Once we're into that quantity, that is it, prepare for engine stoppage in a fairly short time period.

It also relates to use of fuel for pump cooling. If the the white 'pony' tank is mostly full because it first pumps in from the bladder, then there would be plenty of gas for cooling until the very last 1/4 gallon.

BTW, if you lose interest in the little tank, let me know and we might be able to 'do a deal.'

Thanks,
Bob Wilson

[galaxee]

Bob,

check the OP again, i did add in pics of the sub-assy after he took it apart. i should have made that more clear.

[bwilson4web]

<div class='quotetop'>QUOTE(galaxee @ Apr 25 2007, 10:38 AM) [snapback]429782[/snapback]</div>

Bob,

check the OP again, i did add in pics of the sub-assy after he took it apart. i should have made that more clear.
[/b]

Thanks!!

It looks like the bottom of the 'all in one' box is gravity fed from the bottom of the bladder. This means the 'unusable fuel' would be what pools around the side and doesn't drain into the 'all in one box' and reach the fuel pump pickup port.

Could you hazard a guess about the relative height of the fuel pump take up port and the bottoms of the 'all in one box' and the bladder? I'm trying to figure out where any residual gasoline might reside and rough order volume.

Any possibility of another photo or two with a ruler so we can figure out the rough dimensions?

Also, if you would, please measure the minimum and maximum resistance of the two variable resistance arrays. There were some early reports about the voltages measured from the sending units and the step functions were consistent with the resistance array shown in the photo. Knowing the resistance ranges gives us insights about the actual circuit including the fixed resistor and likely drive voltages.

Can you tell if the fuel pump motor has brushes or is it a brushless design (only because I'm curious.)

Thanks,
Bob Wilson

ps. Sorry I missed the update. Great photos!

[hycamguy07]

Very nice! OMG! So much for thinking its just a standard gas tank like the older cars.....

Theres alot of stuff inside of the metal covers......

[galaxee]

<div class='quotetop'>QUOTE(bwilson4web @ Apr 25 2007, 01:27 PM) [snapback]429912[/snapback]</div>

It looks like the bottom of the 'all in one' box is gravity fed from the bottom of the bladder. This means the 'unusable fuel' would be what pools around the side and doesn't drain into the 'all in one box' and reach the fuel pump pickup port.

Could you hazard a guess about the relative height of the fuel pump take up port and the bottoms of the 'all in one box' and the bladder? I'm trying to figure out where any residual gasoline might reside and rough order volume.
[/b]

maybe a cup or so of gas could reside in the box given the height of the fuel pump intake, as far as what's left in the bladder there are some expansion bellows that may keep the last bit of gas in the bladder once the bellows return to near-collapsed position.

Any possibility of another photo or two with a ruler so we can figure out the rough dimensions?

Also, if you would, please measure the minimum and maximum resistance of the two variable resistance arrays. There were some early reports about the voltages measured from the sending units and the step functions were consistent with the resistance array shown in the photo. Knowing the resistance ranges gives us insights about the actual circuit including the fixed resistor and likely drive voltages.
[/b]

unfortunately everything but the resin bladder is gone at this point

Can you tell if the fuel pump motor has brushes or is it a brushless design (only because I'm curious.)
[/b]

pretty sure it's a brush motor design.

[ozyran]

Thanks for the educational trip through...the gas tank (dun dun da!)

Seriously, though, that looked like it tool a long time to disassemble and compile. Your efforts are commendable.

[wyounger]

<div class='quotetop'>QUOTE(Oxo @ Apr 7 2007, 12:35 PM) [snapback]419418[/snapback]</div>

Very useful and interesting - all 25 pics! I wonder how many hours it took Toyota's people to design it?

Am I wrong in thinking that European models of the Prius do not have a bladder? Is there any easily visible external evidence that a bladder is fitted?
[/b]

The bladder is fitted in US models in order to qualify for the PZEV emissions rating in California and the handful of US states that have adopted the California emissions standards. They could have made the bladder just for those states, but elected to just put them in all Priuses. The Prius is not the only car that has a bladder-type fuel tank now, either; offhand I am aware of PZEV models of the Camry, Focus, Subaru Legacy, Nissan Sentra...

The reason they all are adopting the bladders is that the PZEV standard prescribes, on top of hydrocarbon, NOx, etc., limits, a specification of ZERO evaporative emissions while the car is parked. In most cars, even with an evaporative canister, some fuel still manages to evaporate out of the tank. By adopting the bladder, the fuel doesn't ever have an air space around it and no evaporation can occur.

I have no firsthand experience of it but I have read that the bladder is not included in Prii sent elsewhere in the world. I don't know what you might find in a Canadian model, either.