Hi,
Quote:
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Originally Posted by SoopahMan
I'm still in the dark as to why it's a "bladder" - and by the way the title of this thread is pretty funny. UTpiper, I hope you've taken care of everything.
I've read the bladder "reduces vaporization." But vaporization where and to what benefit? The fuel vaporizes.. in the tank? Is that bad? Somewhere further down the line? Why would a bladder affect anything after the tank?. . . .
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The USA Prius has a fuel bladder within the metal tank and an arrangements of tubes and valves that controls the flow of trapped gas vapors in the space between the bladder, carbon cannister, a 'Purge line' that goes to the throttle assembly and also operates a "hydrocarbon absorbtion control" for a valve on one of the catalytic converters. I don't know of any good description of how the assembly works although the maintenance manual is good about how to find and fix problems.
We know that in the NHW11 Prius, 01-03, there is a valve on the catalytic converter that can go bad and result in an expensive repair action that is part of the system. There have been suggestions to lubricate it with a high temperature lubricant. My understanding is the 04-current Prius uses the coolant canister to avoid this hydrocarbon absorbtion assembly but I don't have any details.
There are a lot of unknows about the fuel system and speculations that the bladder volume is temperature sensitive. One of these days, I plan to put a low-pressure range gage to measure the pressure in the space between the bladder and tank. But the effect, a variable size fuel tank, has been pretty well confirmed.
This means individual, calculated fuel tank mileage is subject to substantial variations (see my vehicle log.) But the overall average across multiple tanks is accurate. It is one of those 'nagging problems.'
Bob Wilson