: Fuel gauge



JAYRAT
12-19-11, 09:44 PM
Once my fuel gauge reads half i can literally see the needle move down fast. Is it reading true? Does anybody have same issue or any suggestions.

EChas3
12-19-11, 10:11 PM
That's normal.

When the low fuel warning comes on, refuel ASAP. You may have less than a gallon.

ddalder
12-19-11, 10:30 PM
There are several possibilities, but I don't notice this with mine. Fuel senders and interpreting their signal is a little different than many years back. Manufacturers have compensated for the odd shapes of some fuel tanks.

JAYRAT
12-19-11, 10:46 PM
Well sounds like an excuse for road trip in the car. My wife drives it way more than I do and to her it's not normal on the fuel gauge fidelity, but when i drive it (which majority of time is highway) cruise control is at 80 mph so I also notice the needle moving down after half. I figured going 80 your fuel level will drop considerably fast, so in conclusion I will drive it and pay attention to fuel level and distance. Then I will make determination if she is correct on her argument of the fuel gauge. I don't know of any other way to investigate this, any suggestions?

Smiling Jack
12-19-11, 11:48 PM
Well sounds like an excuse for road trip in the car. My wife drives it way more than I do and to her it's not normal on the fuel gauge fidelity, but when i drive it (which majority of time is highway) cruise control is at 80 mph so I also notice the needle moving down after half. I figured going 80 your fuel level will drop considerably fast, so in conclusion I will drive it and pay attention to fuel level and distance. Then I will make determination if she is correct on her argument of the fuel gauge. I don't know of any other way to investigate this, any suggestions?

You could fill up and then record a log of fuel used from the driver info center vs. mark indication on the fuel gauge from indicated full to indicated empty. Note: You may need to burn off a few gallons until the needle moves off of the full mark, and you may still have a gallon or two of fuel reserve remaining at the indicated empty mark; so even if the tank holds a nominal 17 gallons, it may take only 13 or 14 gallons to move the needle from full to empty.

kschwed
12-20-11, 07:35 PM
Does an indicator light actually come on when the fuel is very low? I've ran the tank down pretty low (Gas pump clicked off at 16 gallons), but no light or chime had occurred.

Greg00coupe
12-20-11, 08:37 PM
Mine comes off full a little slow like any car I ever had. Drops a little slow to 1/2 but does not move that quickly to E. My low fuel light and chimes come on just about E and I've ran 25 miles after but was concerned. Rarely do I allow it to drop below 1/4. Bad for the fuel pump.

mckellyb
12-21-11, 06:50 AM
1/2 a tank, indicated by the gauge, is less than 1/2 by a few gallons. Not all cars are like this, but many GM's are. My wife's RX300 is spot-on, and on the old Suzuki Grand Vitara I used to have, the gauge moved off 'F' within 10 miles of driving. The gauge on that trucklet, a 1999, was the only truly well-built part of it.

The low-fuel indicator/chime goes off when the car calculates you have 50 miles left. For me, it's usually a bit more, but it varies with temperature, and of course, driving/traffic.

I routinely run mine into the low-fuel area and put 17-18 gallons in. I've accidentally run it dry, one time, because that one time, the distance to empty was actually less than what was indicated by the car (by about two miles, according to my calculations).

JAYRAT
12-21-11, 09:02 AM
I ran the car till computer said low range. i filled it up and it only took 13 gallons, the needle was on E. that to me means I had 4 gallons left? Thats When I noticed my range was 263 miles full, which before when i would fill up range would be 300+. So i am thinking something is wrong somewhere. Its really cold here maybe thats it.

Angus Young
12-21-11, 12:22 PM
I fill up from dead empty every other day, I drive I-95 160 miles per day at 80 mph, once you get a click or two under 3/4 tank it starts dropping FAST, the low fuel light only comes on when the needle is completely on empty, I have never gotten more than17 1/2 Gallons in that tank, I have seen the needle below the empty line. Once you go over 78 mph the N* gets very thirsty. I currently have 163,000 miles on one of my 2 05 STS's

Smiling Jack
12-21-11, 01:32 PM
I fill up from dead empty every other day, I drive I-95 160 miles per day at 80 mph, once you get a click or two under 3/4 tank it starts dropping FAST, the low fuel light only comes on when the needle is completely on empty, I have never gotten more than17 1/2 Gallons in that tank, I have seen the needle below the empty line. Once you go over 78 mph the N* gets very thirsty. I currently have 163,000 miles on one of my 2 05 STS's

Our car's daily mileage is on the other end of the spectrum - average of about 10 miles a day.

I think I will start a log of gallons used (from the DIC) vs. fuel gauge indication.

The good news is that I will get really good resolution by reading only once a day.

Bad news is it may be quite a while before I can post much data.

EChas3
12-22-11, 10:51 PM
The low-fuel indicator/chime goes off when the car calculates you have 50 miles left. For me, it's usually a bit more, but it varies with temperature, and of course, driving/traffic.

Our (my wife & I) 2 N* STS don't vary much at all. When we see the warning, it has about one gallon left.



Once you go over 78 mph the N* gets very thirsty.

I find the N* starts gulping above 2,000 RPM. In my car, that's not much more than 60MPH. My wife's car gets to 80 MPH before MPG drops below 25.

Smiling Jack
12-28-11, 01:49 PM
The fuel gauge in my 2006 STS has eight divisions between the empty and the full indications.

The owner's manual gives the tank capacity at 17.4 gallons.

Today, I put in precisely 8 gallons. The fuel gauge read just shy of 1/8 tank before the 8-gallon fill, and it read just shy of 5/8 tank after the fill.

That would indicate that the gauge reads 8 gallons for the lower half of the gauge range. This seems to contradict the opinions posted here by some who believe that the gauge drops more quickly below the 1/2 mark.

I will now start logging the fuel used vs. the gauge indication from 5/8 down to near empty. We will see from this how linear my gauge appears to be in that range.

dkozloski
12-28-11, 02:06 PM
The gas tank is saddle shaped and straddles the drive shaft. Once the level gets down to the bifurcation the level drops pretty quickly.

Smiling Jack
12-28-11, 02:24 PM
The gas tank is saddle shaped and straddles the drive shaft. Once the level gets down to the bifurcation the level drops pretty quickly.

I understand the logic here, but this opinion seems to be in conflict with my readings, so far. I hope my log through the bottom half of the gauge will shed more light.

Perhaps you or some others will repeat my little experiment of adding precisely 8 gallons when near empty and recording the change in gauge positions.

Any confirming or conflicting results would be much appreciated.

Frikiton
12-29-11, 12:53 PM
I always see 40-46 miles range remaining before the low range only comes on.

JAYRAT
01-02-12, 05:11 PM
So the road trip was to west texas and back home total miles, round trip 172 miles. 8.5 gals were used, was marking between 3/4 and 1/2 mark. So average speed 80 mph comes out to est. 20.2 MPG Now that was from full tank next is from half, so i guess thats half of the experiment. tba

ddalder
01-02-12, 05:20 PM
The gas tank is saddle shaped and straddles the drive shaft. Once the level gets down to the bifurcation the level drops pretty quickly.
This should not make much difference. A lot of vehicles have odd shaped tanks now. Two methods (I'm aware of) that manufacturers have used to compensate are:

1. Windings on the sender are not perfectly linear and compensate. Not very reliable.
2. The PCM maintains a table that translates the voltage sent by the sender to the remaining fuel left. This allows for fairly accurate compensation due to odd shaped tanks.

My gauge seems to drop in a fairly linear manner.

BLACKllac
01-03-12, 12:15 AM
i also have horrible gas mileage. i was going to post something but i figured there were already threads concerning poor gas mileage. anyways, i have an 07 v6 and get very, very horrible gas mileage. i can literally see the gas gauge move down within just a few miles. is this with all caddi's? i also have a 3.8L grand prix which gets waay better mileage.

Jesda
01-03-12, 01:49 AM
You'll have to be more specific, by posting MPGs.

BLACKllac
01-03-12, 01:53 AM
just put the 'lac away for winter... ill have to follow up in the spring. thanks anyways