"Running on Empty"

If it makes you feel any better, I don't really think anyone is calling you stupid.

I'm on the other side of the spectrum..I fill up once a week regardless. The plus side is it doesn't take very long and if something ever happens to prevent gas stations from operating, I'll still be good to go.

 

WOW - this topic seems to have really hit a nerve with a lot of people! I admit that all of my arguments are weak, but you asked "why" so I tried to respond.

Looking at it the other way:
1. The electric fuel pump is mounted to the bottom of the gas tank, so most likely the tank itself will heat sink the pump and protect it from overheating. And we know that Bob has already done this experiment on multiple occasions with no apparent ill effects.
2. Unlike the previous generation Prius, the 2010 reserve fuel capacity is very predictable, with about two gallons remaining after the the gauge shows empty. So if you're driving a road that you're familiar with, it's fairly easy to predict your mileage (e.g.) at 55mpg you've got 110 miles reserve, so 80 or 90 miles is fairly safe, even without a spare can of gas. And unlike most cars, you don't need to worry about major traffic jams running you out of gas since the Prius doesn't burn any fuel when you're not moving.
3. Who cares about crud plugging up the fuel filter -- the 2010 is new and it typically takes years for that kind of crud to build up.

 

If you are refering to my post in the above quote I would like to bring your attention to something. I didn't call you stupid, I'm sure you are not sir, what I said is the behaviour is stupid, that is all.

 

As of this post lutece7 has 38 posts. Here is a guy new to forum with a somewhat different but valid question and he is welcomed like this. I would ask all of the people in this thread to evaluate your responses and consider how you would feel if you were a new guy asking questions.

Now for my comment on your question. I think it is a valid thing to know how many miles or how much gas is still available when the ticker goes to zero. I welcome your findings. Be safe.

Some of the points made by above posters are good points. I wish the people that did berate you were more considerate.

So let me welcome you to the forum. There is a lot of good information here. I hope you have not been turned off by the attitude of some.

 

The 2010 Maintenance Manual shows that the fuel pump assembly can be replaced. The North American Prius had a bladder so the whole tank had to be replaced and there was a real risk from over-filling.

Galaxee's DH disassembled a bladder tank and posted the photos a year or so ago because it had been overfilled. The former tanks were sealed units so the whole tank had to be replaced at about $1,500 ... non-warranty repair. Worse, the fuel indicator from flash to empty ranged from as low as just over 25 miles to a high of 134 miles.

Now I want to make it clear:

• Running out of gas is not recommended - because there is no warning light when the last of the gas is gone. If someone is not aware of this, they can run their traction battery down before they find a safe place to park.
• From FLASH there is ~2.1 gallons remaining - reset one of your trip meters and use the distance and fuel consumption rate to calculate the amount of fuel remaining; cut your speed to maximize your range; and fill-up at the next opportunity.
• Testing for fuel gone - punch the accelerator to see if engine spins; watch the traction battery SOC and see if it is going down.

So let's also address some vehicle risks:

• fuel pump overheating - the fuel pump is driven by the ignition controlled battery bus. Turn off the car and there will be no more electrical energy going to heat the fuel pump. Turn off the car when it is out of gas. However, you may need to run the emergency flashers (I need to find out if the emergency flashers run when the car is off.)
• catalytic converter burn-out - when the engine runs out of gas, it rapidly transitions through lean to no longer producing heat. It would take sustained operation at high heat to do damage to the catalytic converter and the transition to 'out of gas' is pretty rapid.

It is easy to avoid running out of gas. But sometimes, sh*t happens and when it does, DON'T PANIC. If you catch it soon enough, use the traction battery to get to a safe place and then get some fuel. If not, your car will soon lose traction battery power so coast to the least bad place to stop and then get some fuel.

Bob Wilson

 

I thought that the person actually doing the out-of-fuel testing (you?) said that once the gas was gone, the 2010 Prius would NOT continue to run on any remaining traction-battery power.

I thought that the NOT being able to use the battery to get to the side of the road was exactly the safety issue with the 2010 Prius.

Am I wrong?

Added: I now see that you later discovered that the 2010 Prius WILL continue to run on the traction battery, though perhaps only for a very short distance - depending upon the state-of-charge when the fuel runs out.
Also, there is no obvious warning that one is out of fuel, so the event (and the resulting transition to battery-only power) can be easy to miss. So, you recommend: Plan Ahead to NOT run out of fuel.

THANKS for the update here in this thread, or I might have missed it.

 

As I'm sure you know it's not going to hurt a thing and it's a very good test. I've done the same thing on dry pavement, you need a very large very empty parking lot. It's good to observe the operation of the VSC system and notice what the lights do and what the effect on the throttle is. It's also good to know what the car feels like near the limit of adhesion. I test my ABS by using it on an empty stretch of highway at several different speeds so I will know what to expect if (or when) I need to use the anti-lock brakes for real.

Keep experimenting, I think it makes us safer and more knowledgeable drivers as long as we temper our experiments with a little common sense.

:rockon:

 

It took three fuel exhaustion tests to figure it out:

1. I was on a down grade so gravity, momentum and a handy parking lot and I was able to park out of traffic and add the extra gallon. The only indication I had was the "electronic steering error." In this case, I had no reason to try the accelerator so I didn't realize the traction battery power was not available.
2. In this case, I was at about 45 mph on a gentle up grade when the "electronic steering error" came on. I was surprised to find there was no remaining traction battery power. Fortunately it was about 3:00 AM and there was no other traffic. I had enough momentum so I shifted into "N" to inhibit regenerative braking and coasted into a parking lot about 100 yards away. This really bothered me because I didn't know if between the actual last gas burn and the "electronic steering error," there was any traction battery power. Also, the error light was misleading.
3. This last case, I was on I-565 at 70 mph and knew it would run out of fuel any moment. Since I was approaching an area I didn't want to run out of gas, I took an exit to make a U-turn. When I started to accelerate on the on-ramp, I realized the engine didn't start and it was truly out of gas. But I was only down one bar on the traction battery SOC. I was quite relieved that I could use the traction battery to move down the shoulder ~200 yards where I put in the spare gas.

But sometimes it is hard to get this across in a posting.

No problem! I fully realize how difficult it is to get something as involved as running out of gas described in a way that everyone understands. I have no problem with sharing my 'lessons learned' if it helps folks to understand and deal with it.

I ran the car out of gas deliberately because I also like to do gasoline studies and this is the best way to switch between gasolines with a minimum of mixing. The earlier NHW11 and NHW20 were very good about throwing up a dashboard full of error lights when the last of the gasoline was gone but our ZVW30 doesn't.

I understand Toyota believes this 'stealthy' behavior meets the vehicle design specifications. As I've pointed out, I think it is far safer to give the driver some indication when the last of the gas is gone so they can use the remaining traction battery power to reach a safe place.

My best estimate is the PriusChat community is a small fraction of the total Prius owners, less than 1%. If my worst fears are realized, something bad may happen in the pool of the other 99% of Prius owners. That will be reflected in an accident statistic but hopefully NOT BY ANYONE HERE! It would be best if I am wrong but a simple risks analysis suggests otherwise. I'm patient ... and sharing what little I've learned with the community.

Bob Wilson

 

I, for one, APPRECIATE VERY MUCH your sharing and your careful observation of your thoughtful experiments.

I agree, there should be some very noticable "gas gone" indication.

Please, what are the NHW and ZVW designations - where do they come from?

Oh, from the Prius Glossary, I see that there are "chassis codes":

NWH-10 = Japan Only = 1997-1999 (Gen0 ?)
NWH-11 = Gen1 = 2000-2003
NWH-20 = Gen2 = 2004-2008
ZVH-30 = Gen3 = 2010-...?

What happened to 2009?
Probably NWH-20 also (Gen2)?

 

i will tell you how far i have gone past zero on DTE if you tell me what your avatar is supposed to be. i m guessing its a car on a lift, but what car is it?

 

oic...i guess??

why your wheels so bent out like that?? is that a parallax/fisheye/ photoshop kinda thing??

anyway.

on one tank, i did go 73 miles past the DTE Zero mark. or 121 miles past the "beep"

pretty sure i had another 50 miles to go

 

Take a look here for some great photos: http://priuschat.com/forums/gen-iii...-photos-taken-bottom-my-prius.html#post951504

It explains how lutece7 has been thanked 68 times with only 40 posts total!