Low fuel warning -- how many gallons left? [Archive] - B15sentra.net - Nissan Sentra Forum

: Low fuel warning -- how many gallons left?


SeeksMoltnSpecV
03-25-2002, 04:21 PM
I quote from the 2002 Sentra manual, page 2-9:


Low fuel warning light
This warning light comes on when the fuel in the tank is getting low. Refuel as soon as it is convenient, preferably before the fuel gauge reaches E (Empty).

There will be a small reserve of fuel remaining in the tank when the fuel gauge reaches E (Empty).

Does anyone know how many gallons are left when the warning light first appears? Other cars I've owned have stated "approximately two gallons remain," or something similar. This at least gives you an idea how much further you can go (assuming you know your typical MPG).

So what about the Sentras? When the light comes on and the manual says "fill as soon as convenient," do I have enough go juice to make my 33mi commute that day? (My SpecV is currently giving me 27-28MPG). It would not be convenient for me to stall...

Maxx
03-25-2002, 04:51 PM
The light does not come on at the same time on every tank. It will come on sooner if you are doing city driving (more fuel left,) and later if you are doing primarily highway driving (less fuel left.)

I have had it come on with less than one gallon left (!!!) and as much as 3 gallons. On average, I would say it has roughly 2-ish gallons left.

SeeksMoltnSpecV
03-25-2002, 04:59 PM
Are you implying that the ECU guesses how much range you have left based on recent mileage/efficiency. It then then warns you when it thinks the time is appropriate?

The specs in the manual say the tank is 13.25 gallons. So by putting in just over 10.8 gallons, I guess I had a little under 2.5 left.

I realize it's not practical to squeeze out the last possible drop and run the tank dry. I just wish I had a better predictor of when I really need to fill up. You know how sometimes you're in a rush, and you'd rather fill "later...."

With my previous daily driver, I pretty much ended up ignoring the gas gauge [they're all inaccurate to greater or lesser degree] once I got my pattern down. When that car's trip odo read 350, there was consistently one gallon left. So I pretty much used that as an indication. I'll end up doing the same once my SpecV and I are used to each other, and we are both fully broken in.

Maxx
03-25-2002, 06:54 PM
The information on the light coming on at different times was based on what I read in the owners manual of my '01 car.

I think mileage is definately the way to go. My car will go 280--290 miles typically with my mix of city/highway driving. My fuel gauge is all whacky. It will stay on full till about 80 miles, then falls slowly to 1/2 tank, then drops like a rock for the last 1/2. It isn't a very good indicator of how much fuel you actually have left.

SeeksMoltnSpecV
03-25-2002, 08:44 PM
Originally posted by Maxx
...then drops like a rock for the last 1/2.
This seems to have been true of every fuel gauge I've ever seen. A friend theorizes that it's because many tanks are V shaped near the bottom.

Even though the needle doesn't drop at a consistent rate, it is useful. If it's above 1/2, you have "lots." When it starts diving from 1/4 to E, you better be lookin for a station.

SR20dee
03-27-2002, 06:28 AM
ive actually ran out of gas.(cus im dumb). when the gas light comes on...(just turned on)and i fill it up it sucks 11 gallons... so figure maybe 2 gallons a lil more..

2002XE
03-27-2002, 07:23 AM
the low fuel indicator came on approximately 10 miles from the gas station and the car swalloed 11.6 gallons of gas.

I try not to let the indicator turn on because there isn't much gas left at that point and I could be SOL if I am far from town (central Texas).

Roger

deliriou5
03-27-2002, 08:06 AM
Believe it or not, I once filled up with 13.31 gallons of gas!! That's more than the actual tank's capacity. Of course the station attendant guy topped it off, but it was scary! I know I was running on fumes, because I had trouble starting the engine that morning before I got to the gas station. In my observation, the low fuel light gives you about 50 miles of driving before empty.

McGarrett
03-27-2002, 11:42 AM
Originally posted by SeeksMoltnSpecV

This seems to have been true of every fuel gauge I've ever seen. A friend theorizes that it's because many tanks are V shaped near the bottom.

Even though the needle doesn't drop at a consistent rate, it is useful. If it's above 1/2, you have "lots." When it starts diving from 1/4 to E, you better be lookin for a station.


Actually, this non-linear reading of the fuel gauge is intentional. I forget the source but back in college, one of my classmates did a research paper on this very phenomenon. His brother was an engineer at GM and apparently, they designed the gauge to drop faster after the 1/2 mark for 2 reasons:

1) To give the illusion of better fuel economy. Apparently, people pay closer attention to the gauges right after fill up. When it drops slowly, they feel more comfortable driving.

2) To help prevent out-of-gas situations. According to his paper (IIRC) people were more likely to run out of gas if the gauge dropped consistently. If it drops more quickly as the tank empties, it creates a sense of urgency that makes the driver stop for gas toute suite.

Other automakers soon applied the same criteria to their fuel gauges

Please keep in mind that college is quite a few years behind me and I was, well, stoned most of the time ;)

But I did commit certain things to memory and (I think) this is one of them.

McGarrett

AztecRed SE-R
03-27-2002, 12:40 PM
Originally posted by deliriou5
Believe it or not, I once filled up with 13.31 gallons of gas!! That's more than the actual tank's capacity. Of course the station attendant guy topped it off, but it was scary! I know I was running on fumes, because I had trouble starting the engine that morning before I got to the gas station. In my observation, the low fuel light gives you about 50 miles of driving before empty.

Not necessarily, remember, most cars have a small reserve for fuel which is not included in the total amount your tank can hold.

My 94 intrepid has a 60L tank, and I once got 62.5L in there. According to the computer, I had only 5km left before I was outta gas.

CowboyDren
03-27-2002, 02:57 PM
You shouldn't be driving with less than a quarter of a tank. The fuel pump is submerged in the tank, and the fuel is what cools it. Repeatedly exposing the pump to air will shorten it's life. Don't do that.

bigjerm
03-27-2002, 11:04 PM
holy crap, i did not know that about the fuel pump!, but i typically fill up at about 1/2 tank remaining. btw, i hate the fuel gauge, like you all said before, it is very deceiving. if you completely fill up, it stays there a while and proceeds to drop like a rock.

blackserspecv
03-28-2002, 12:38 AM
Personally I gas up every time my light comes on, and sometimes after I get 30 miles after the light turns on. My brother, a mechanic, tells me its bad to do that with the fuel pump. However, he tells me that I should run isoprophyl at least every 3 tanks in the winter, but he forgets that I run my tank dry each time. I figure that by saving $10 a year on treatments, $1.50 x 6 times, I really am not losing much money if I do have to replace the pump in 5 years or so. Plus I always get gas where I know its good, unlike the horseshit gas in my town, which has been known to f#%k up engines in the winter because of water. I get usually about 30 to 35 miles highway after the light comes on, the most I have ever put in is 11.97 gallons, but I did not top it off as much as I knew I could.

JP
03-28-2002, 09:26 AM
I've put 12.8 gallons in before. I drive alott and fill her to the brim and then tap her dry. I usually will let myself go 20 to 30 miles after the light comes on!

LoOoD
03-31-2002, 01:26 AM
when I fillup my spec-v when the gas light comes on , the pump says I've added between 11 and 11.5 gallons... so do the math..


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sentra sm0ke
03-31-2002, 05:16 PM
the light comes on when you have less than 3 gallons left in the tank.

PRSentra2000
04-10-2002, 08:34 PM
I get about 100 miles untill the indicator gets to the "F" then I get about 225 to half a tank then it drops really fast and I get about 320 to 1/4 a tank, thats pretty much as far as I'll let it go.