I'm Losing bars on my Gas Gage, Am I losing Gas too?

Catalytic converter you said? Has there being any code logged on the computer of your car? Any check engine lights? If there are, get it scanned.

 

how could either of those lead to loss of gasoline? i thought it was the bladder.

 

They won't. Neither will a bladder fault unless it has a hole; it will only cause a loss of tank CAPACITY which is quite different than a loss of fuel.
I think the OP doesn't really understand anything about how car engines work........and is taking some things completely out of context.

 

So does the O/P actually have a gas cap???? Have you brought it to Toyota and had a scan for codes done.... are you running on only 3 cylinders? You don't lose 2 pips going only 40 miles..... something is amiss........

 

$24. iirc.

 

I am sorry for the turn that this thread has taken, and some of my posts.
The problem here is confusing wording of the original and subsequent posts by the original poster.

Using the right words is important.
LOSING gas is quite different than USING additional gas.

If there is a gas leak (losing gas) there should be a strong gasoline odor somewhere.
While that is possible, an injector stuck open maybe, it is highly unlikely.

So the real question should have been: What will cause me to USE additional gas when my MPG drops drastically ?
It appears that you are on the right track for diagnosing that problem.

But two things:
Getting a professional opinion (not just looking up a code in a book) is still a good idea.
Your car is OLD and sinking a lot of money into it probably isn't wise.
Good luck. Keep us posted.

 

Although the Gen2 gas tank is designed for 11-gal especially in winter about 8-gals fill-up is normal, but as the cars age that can go down to 6-gals in winter...not sure why except to say the flexible tank may lose some flexiblity/volume especially in cold weather.

You could lose 2 bars pretty fast if it is the first 2 bars...in my case in winter I can barely get enough gaso in there to to tick off a full 10 bars, then you can lose the top two bars fairly fast. Other situations also ..you need to realize there is programming behind the pips, for example you never see gaining a pip on a hill or something.

As far as cat converter you can live with that as long as it passes inspection. If you want to fix, those of us in non-CARB states can go with a cheaper replacement converter from EBay. Usually a bad cat converter infers oil burning and the metal additives in the oil mess up the cat converter.

 

Cat converter has nothing to do with fuel consumption. Some posts on this site about cats being clogged causing poor engine performance though. Clogged cats caused by high engine oil consumption from very worn engine.

And oil filter is well.....an oil filter. Nothing to do with fuel consumption.

There are mainly just few things to cause very poor mileage and bulk fuel loss.

You have a fuel leak
Engine very worn piston rings shot on Prius usually caused by extreme high miles or poorly maintained engine and sees and saw huge oil loss and rings damaged
Or the best guess is the hybrid battery is really old and not contributing any power making engine do all th you’ll know this as there will be or soon be a lot of lights on the dash the rear fan on and or engine always screaming.

 

BAD advice, Ed.
Where DO you get some of the stuff that you throw around ??

No, never mind. It's obvious that you don't grasp that every thought that pops into your head is NOT a brilliant revelation.

 

Man you are such a ball breaker.

 

Ed is basically correct...the cat converter is treating your waste gas after it is made...although it might have a secondary impact if the cat temp is low it might delay warm up stages not sure...

You have not even convinced us you have low MPG anyways. MPG will be in the gutter in this frigid cold. That plus short trips could get you 30 MPG in this weather.

 

Rock Auto show this Prius with two O2 sensors the question is which one is bad. Yes a catalytic converter can be a cause of poor gas mileage. Your engine is an air pump and works best when it can move as much air as possible through it. The O2 (Oxygen Sensor) measures the amount of oxygen in the exhaust and tell the engine computer to adjust the amount of fuel that is injected into the engine to keep it at the right fuel air ratio. O2 sensors don't last for ever and I am sure catalytic converters don't either. It sounds like you need to put some faith in someone and get the car diagnosed and fixed. JMO

 

sounds about right, might be more at a dealer.

 

I have been learning about O2 sensors, The first one is referred to as the upstream sensor and it does most of the work and is the one closest to the engine. The downstream O2 sensor is after the catalytic converter and it measures catalytic converter efficency. An engine that burns oil or leaks antifreeze into the exhaust are bad for catalytic converters.