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Discussion Starter #1
I have been reading about the gas gauge on the Prius and it's warning message about damaging the Hybrid System if such occurs. Has anyone ran out of gas yet and experienced what happens? Has anyone checked with the service department of their dealer and gotten an answer?
 

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Dunno - all I know is what I've been told: NEVER EVER RUN OUT OF GAS WITH THIS CAR. That's the reason the gas gauge is inaccurate - people seemed to think they could run it without gas. I can't answer your question, but I hope I won't ever be able to.
 

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That's the reason the gas gauge is inaccurate
No, in Europe its accuracy is normal, because we don't have the so-called "bladder" to minimize evaporative emissions. Anyway the hybrid system never allows you to completely deplete the battery, even if you run out of gas. But probably other parts in the engine could be damaged if you did so. Remember : this is NOT an electric car, this is a gas/petrol car ! :wink:
 

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run out of gas intentionally

After watching the gas guage flash on empty for almost 100 miles, I decided to drain the tank on my 2004 to see what would happen. My guess was that it would set off alarms and run on the battery until the battery fully discharged. But, obviously, I wasn't about to let that happen knowing the warranty would be voided and I'd be spending thousands on a new power pack. I made sure to continue to drive in an urban neighborhood where I knew of three different gas stations, each within a mile of the other, and after a while (at just over 400 miles on the trip odometer) the triangular warning light came on along with almost every other symbol of doom on the dashboard. Knowing I was driving on battery power alone, and switching the LCD screen to the battery icon to keep an eye on the charge level, I continued to drive until only two bars were left on the battery level indicator. I was unable to drive over 20+ mph and only managed to put a few miles (up and down hills) on the car before my will power gave out and I pulled into a gas station to refuel. After filling the tank, I powered up the Prius and all the warning lights were now off. The battery recharged during the subsequent 5 miles. The car ran mainly on ICE until the battery level stabilized. The lesson learned: don't run out of fuel if there isn't a service station within 3 miles or unless you have a long stretch of downhill road to get you to your next fill-up. An uphill grade drains the battery very quickly and, unless you have a ton of courage, it isn't worth the stress derived from watching the battery bars drop to near zero.
 

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Discussion Starter #5
To Jefff

Talk about courage! Your story is fascinating. It would seem to me that Toyota would have intentionally ran out of gas to see what would happen and give specifics, such as you did, as to the best action to take in case of this situation.

Kudos to you for having the motivation to "test" this scenario. I'm glad your Prius seems to be functioning well instead of falling apart after the intentional draining of the fuel.

Thanks for the info. You should at least put a reference to this post on every section of this forum so people will gain from your experience.

Thanks again.
 

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Discussion Starter #7
Grammar lesson

I don't know why I do that! I do it all the time. It seems that I just can't resist those apostrophes!! LOL Thanks for the lesson. As you can see, I didn't make it to college.
 

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re: Henry

As you proofread, rather than constructively contribute to these postings, am I to feel relief or rejection over the fact that you neglected to point out that I misspelled "gauge" (note my "guage")? Just curious.
 

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Thanks for the report, Jeff. Based on the urgency of the warnings, I imagined that running out of gas would destroy the engine (perhaps inducing the computer to put it into a perpetual trying-to-start cycle).

That said, I'm still going to fill up as soon as the last bar blinks, if not sooner.
 

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As jefff12 mentioned, if you run out of gas in a Prius, you can continue to drive slowly a short distance. The main reason I've heard for not doing this, and for avoiding running out of gas, is that the fuel pump is cooled by gasoline, so it experiences extra wear from overheating. This might shorten its life. The fuel pump warning is general automotive information, it is not Prius specific, so it probably applies, but might not.
 

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RSnyder said:
As jefff12 mentioned, if you run out of gas in a Prius, you can continue to drive slowly a short distance. The main reason I've heard for not doing this, and for avoiding running out of gas, is that the fuel pump is cooled by gasoline, so it experiences extra wear from overheating. This might shorten its life. The fuel pump warning is general automotive information, it is not Prius specific, so it probably applies, but might not.
there's that, and you also drain the hybrid
battery down further than usual. Too many
stop and reboots before refiling with gasoline,
and your car isn't going anywhere without
a tow to the dealer and a few day wait
for the special hybrid battery charger to
arrive... You could shorten the life of
the hybrid battery, much like the
shortening of life of the 12v battery if
left flat/undriven for many weeks.

basically: like with any car, do not
let the gasoline run out. However, the
Prius will let you limp to a safer
location (depending on initial battery
SOC and terrain), whether that be
only to the side of the road, or a
mile or two until the next service station.

However, do note that the "out of gas"
code will be stored in the car's computers,
there for the next service tech to read...
If you're worried, unplug the 12v battery
for about 5min to clear the codes
(and your preset radio stations,
Nav settings, etc.)
 

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Thank you Jefff12 for that research! You're brave.
And thank you mrv & RSnyder for your always welcome info.
It sounds to me like running out of gas is more trouble than it's worth, and easy enough to avoid, but I would like to see an EV mode button on my dashboard.
 

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I ran out of gas on my first tank on my 2001 model. I was trying to see if I could get 500 miles out of the tank, but I did have to go up 2000 feet in elevation. I was going to fill up when I got back down to the bottom of the hill, and I went 5 miles or so on the flat, but then the warning came on and I could only go about 2 more miles on the battery. I got a ride to a gas station, put some gas in the tank after much fooling around with the lever to open the gas tank flap, and went on my way. Everything was fine after just about a minute or two. I only made it to about 480 miles.
 

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Ran out of gas today on purpose

I have an 04 Prius I got in Dec. The gas gauge begins blinking with approx 2-4 gallons remaining. I ran the car out of gas on purpose. Several warning lights came on (including the big !), the car shuddered the usual gas engine out of gas shudder and then ... it stopped shuddering and the gas engine quit for good. I then drove on normally solely on the electric power, about 5-6 blocks right into a gas station. End of story, except my mechanic suggested replacing the gas filter. I am extremely pleased with this car, and have just over 11,000 miles as of 4/15.
 

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I attended an 'Engines of Change' session before I got the car in Dec. I asked the 'Professor" at Toyota U that question, as I ordinarily run each new car to out of gas in order to know how many miles after the warning comes on (with a jerry can in the car, of course). I had heard dire warning of an uncooled fuel pump burn out and sucking up the sediment at the bottom of the tank and killing the traction battery. He said "no problem" The CPU protects the battery, the pump does not die.
 

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I ran out of gas in my '02 once. I was able to get to a gas station only a few miles away, but the battery gauge was down to the last bar (25%), so I know it can only get you a few miles (maybe as much as 10 miles if the battery was fully charged). I got a bunch of warning lights that disappeared after I filled it up and started it again. It also logged some DTCs, which the Toyota guys checked and cleared. (The DTCs were just of the "hmmm, the engine won't start" variety--no indication of additional problems.)

I don't think the battery will last long enough for the fuel pump to overheat. And, yes, the CPU will shut down the car before the battery is drained to damaging levels. However, I've heard that when this happens, the car cannot be started until the main battery is recharged by a Toyota technician. Attempting to jumpstart it won't help, because that only charges the accessory battery, which is not dead. You can't charge the main battery externally--it must be removed by Toyota and connected to special equipment.

So, I'd recommend not running out of gas. I generally fill up at 2 bars, even though I know I could go farther. If you do run out of gas, use the battery to go a short distance to get somewhere safe (e.g. off the highway). But if there isn't a gas station within 3-5 miles, don't push the battery to the shutdown point.

Douglas (2002 Silver, Wisconsin)
 

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stancy said:
I have been reading about the gas gauge on the Prius and it's warning message about damaging the Hybrid System if such occurs. Has anyone ran out of gas yet and experienced what happens? Has anyone checked with the service department of their dealer and gotten an answer?
I ran out of petrol about two months ago on my 2001 Prius - essentially I wanted to finally work out how far I could go once the fuel warning message appeared.

The ICE engine sputtered a few times as the last of the fuel was used, then the (big) warning message came on and the car switched over to the battery.

I was able to easily get to a nearby petrol station, and my manual does say I can drive 50KM+ on the battery (but it doesn't reccomend it).

Once it was fueled up again everything basically returned to normal! :)

David C. (in Melbourne, Australia)
 

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dcstar said:
... my manual does say I can drive 50KM+ on the battery (but it doesn't reccomend it).
I wouldn't trust that 50km number, because it doesn't match up with other out-of-gas stories I've heard. Let's use some sample numbers to get a theoretical maximum distance:

1. The main battery is rated at 6.5 Ahr.
2. Maintaining a constant 25 mph along a fairly level stretch of road requires about 10 A when the ICE is off.
3. So, if the main battery is at 100% SOC, it will be completely drained after about 40 minutes.
4. At 25 mph, you will have traveled 17 mi (27 km) in 40 min.

Furthermore, these are optimistic numbers, because your battery will never be fully charged to 100% SOC, and the car will shut down before the battery is drained. Let's re-run the numbers assuming a more normal starting SOC of 65% and shut-down at 20%.

1. This yields 2.9 Ahr available. (0.65 - 0.20) * 6.5
2. 10 A @ 25 mph
3. SOC will be 20% after 18 min.
4. You will have traveled 7 mi or 12 km.

You may be able to squeeze out a few more miles by driving more slowly. I recall hearing that MG2 operates most efficiently around 7 mph (and the drag force will be much lower). However, in order to travel 31 mi (50 km) at 7 mph (which would take about 4.5 hr) on 6.5 Ahr, you would have to be drawing only 1.44 A. The accessories alone draw 1 or 2 A when motionless, so this is not realistic. (Unless it's downhill all the way! :) )

Douglas (2002 Silver, Wisconsin)
 

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I drove about 20 minutes on an expressway going approx. 65 mph after the fuel gauge light started flashing when the engine stopped running and all kinds of warning lights lit-up. Luckily I was able to run on battery only, however I was limited to traveling at 52 mph. As the battery storage started dropping rapidly, I shut-off the a/c, blower, radio, and unplugged my cell phone. When the battery was about 25% full, the speed started lowering. As I pulled off the expressway my speed kept decreasing. I then couldn't go up a slight hill to cross over the freeway to get gas (battery charge only had the lowest light on). I shut-off the engine, waited 1 minute, then started it. The ICE started charging the battery, and a low fuel warning light (red triangle) was lit. I was able to drive about one mile to get to the gas station (was in the middle of nowhere at the time) doing 30 mph (not limited in speed but didn't want to drive fast). Everything worked after refuelling.

Lessons learned:
1) you can't drive as far as you would like after the fuel gauge is flashing
2) we only have less than 10 gallons of usable tank before the system limits your driving (thus making the 11.9 gallon claim only a dream)
 
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