can someone please explain the gas gauge on my car?

[air23cary]

my gas light comes on when there is still a little room left in the meter.......and it doesn't stay on it comes on and off repeatedly even though the arrow is not all the way at empty........does this mean

a. i need gas quick, i am almost all out


b. i am getting low on gas, no need to panic, wait till light stays on full time before going to get gas


thanks for the help.

 

[AdrenilineCrash]

B...

 

[pianoman]

when the light comes on i believe you have 2gallons left, i think thats what my manual says. its either 2 or 2.3 somwhere around there.

 

[Eclipsei95cl]

my gas light comes on when there is still a little room left in the meter.......and it doesn't stay on it comes on and off repeatedly even though the arrow is not all the way at empty........does this mean

a. i need gas quick, i am almost all out


b. i am getting low on gas, no need to panic, wait till light stays on full time before going to get gas


thanks for the help.

my gas light comes on even when there is a lil room left in the meter but i know the reason for that is when i installed some indigo gauges and i guess i wasnt careful and sorta messed up the needle it still goes up and down just that its off a bit.

 

[Thomas91169]

^^^aah me also, my guage wont go under 1/4 of a tank. theres clearance behind the needle, and i can move the guage to empty with my finger, but it just doesnt want to go under 1/4 when its in the car. but no biggie, you shouldnt let it get under 1/4 anyways.

 

[Defiant]

Mine comes on about 100 miles into a tank, then goes out again. It gets serious about 220 miles in, and I usually fill it back up with around ten gallons. Healthy turbo DSMs should get right about 300 miles per tank.

Use your tripmeter, and live by it.

DSM gas gauges are only one of the ....eh.... "lesser" aspects of the cars.

 

[Eclipsei95cl]

Mine comes on about 100 miles into a tank, then goes out again. It gets serious about 220 miles in, and I usually fill it back up with around ten gallons. Healthy turbo DSMs should get right about 300 miles per tank.

Use your tripmeter, and live by it.

DSM gas gauges are only one of the ....eh.... "lesser" aspects of the cars.

WOW i get only 150-200 miles full tank Guess my dsm isnt that healthy.

 

[dave99gst]

far as i no -- when its stays on, you got 20 miles to get gas.

 

[DGajre777]

Something I know about... I'll explain why the the gas light does not stay on, but I'll use airplanes as an example instead of cars.

Most airplanes have a low fuel indicator light and pilots refer to it as an 'idiot light'. In most General Aviation airplanes the sensor is not at the bottom, but on the side of the fuel tank. When an aircraft accelerates the fuel moves aft and if the sensor is in the front the light comes on. If you do a emergency decent or a dive, it will indicate that you have low fuel. We are always told that the best way to know what the light is trying to tell you is when you are in straight and level unaccelerated flight. You are not climbing, not decending, not accelerating and not decelerating. With no G forces excerted on the aircraft, the 'idiot light' reads what it is supposed to read - low fuel, but only if the light is constantly on.

The same principal applies to cars. If the low fuel sensor is in the front of the car and you accelerate real hard the fuel moves aft which causes the 'idiot light' to come on. This only happens when the fuel level is at the same level or below the level where the low fuel sensor is mounted.

Incase you are wondering about the accuracy of the explaination, I'm a Commerical Pilot and a FAA Certified Flight Instructor.

 

[SBstar]

sheesh thats all you can get out of a tank. I can get over 400 course its a n/t and doesn't have anything done yet haha. I'll probably be looking at the same once I get my turbo kit. Yeah I know alot of cars have the light come on then back off and on again. My girlfriends Taurus does that. she can get about 80 miles once the light comes on. I wouldn't suggest going over 20 miles once it comes on though.

 

[jasoncitrano]

mine does the same shit, i'm almost thinking about driving it around my block one day when the light comes on to see actually how much fuel i really have left!!
jc

 

[Defiant]

WOW i get only 150-200 miles full tank Guess my dsm isnt that healthy.

Or is that just when you refill it. How many miles per gallon?

 

[Syndicate13]

I never look at the gas guage. It'll stay at the top for like 150 miles and then just go down to 1/4 tank like that. I made a trip yesterday and went 315 miles before the light came on.

 

[97GS-TSpyder]

i got 230 tot he tank on aorund 13 or 14 gallons

 

[Eclipsei95cl]

Or is that just when you refill it. How many miles per gallon?

Well I wont let it get that empty..when the light comes on and stays on at that point I usually fill it then so like dave said you get like 20 miles after that but i refill once the light stays on..I reset my mileage counter every time i fill up and on an average all in all how i drive by the time its empty it will say 150-160 miles. So give or take i could get like 180 miles to a full tank. I bet i could get more if i like ran 5psi or something but yeah ive gotten used to forkin over 25bucks a week for it Im sure my big ass injectors and 255 play a role too

 

[DGajre777]

Found this link in another forum.. but here it is..

Here's the link.. there's 2 pics on it (if you want to read it from the source
http://www.geocities.com/CapeCanaveral/Cockpit/6144/DSM_Home/2G_Fix_It_Center/flakey_gas_guage.html

If you have a 95+ Talon or Eclipse, odds are you too have a "flakey fuel guage. If your car's guage reads "E" and you fill up with about 10 gallons of fuel, you have this problem. The 2G tank holds about 13 gallons including the filler neck. The FWD and RWD have different tanks, but the same basic problem (and the same solution).

Also, if it seems that your "low fuel" light never comes on, or only flashes occasionally when the guage clearly reads "E", then this is for you. The fuel light is right, you DO still have gas left, about 2-3 gallons (Which is why it flashes, since it comes on at about 2-2.5 gallons)

Project Overview/Theory:

To best understand the theory, we will start with the FWD, since it works the same but has fewer parts. The gas guage in the 2G FWD works as follows: Power from the battery flows through the guage in the dash, throguh a yellow wire to the "sender" unit, and through the sender to ground. Now, the sender is a variable resistor, who's value is controlled by the float. When the float is all the way "up" and the tank is full, the "resistance" is low (4 Ohms). When the float is all the way down, and the tank is empty, the "resistance" is high (106 Ohms). The dash guage simply displays the resistance of the float sender, against a scale of "E - - F".

Now, on the AWD, the gas tank has a "hump" down the middle for the driveshaft to go through, so below 1/2 tank you really have 2 tanks. (Because the one is divided by the hump). Becuase of this, the DSM engineers used 2 senders, one in each half. Each sender is identical to, but have 1/2 the resistance of, the FWD sender. They are connected in series. So, the net result is exactly the same as the FWD, and the same guage and wiring are used in both cars. In the AWD at full, both senders read 2 Ohms, and 2+2=4, same as the FWD.

The "Idiot Light" is a SEPERATE circuit, and has NOTHING to do with the guage at all. You could completely remove it and the guage would still function. And vice-cersa. The "Light" works similar to the guage. Electricity flows from the battery (+12V) through the light, to the sender, and then to ground. In this case, the sender is a Thermistor. A thermistor is a lot like a switch - when it is submerged in fuel its resistance is very high, when its in air it is very low. So, since the termistor hangs about 1/2" off the bottom of the tank, when you have 1/2" of fuel left (2.5 gallons) and the thermistor is not being sloshed under fuel constantly, its resistance falls to near zero, current flows, and the light lights up. The idiot light is exactly the same on both FWD and AWD cars, and is located in the drivers side sender on the AWD cars.

Now, I came upon the realization that my car should be holding more fuel, and I did a ballsy thing. I drove it past E. Waaaaay past E. Think Seinfeld when Kramer test drove the Saab. I went almost 75 miles before I gave up. Now, in this process the idiot light lit solid about 20 miles after E was indicated. It stayed solid all the way to 75 miles, when I filled up and began thinking about what was going on.

The next weekend, on less than 1/4 tank of gas showing, I removed the senders from my car and measured the resistance per the manual. They were within spec. Exactly in spec in fact. So I figured that it has to be a manufacturing defect in the GUAGE cluster. Now, several people have advocated moving the needle on the guage. Well, that works sort of. All you have really done though is move the problem from one end of the scale to the other. Now your guage will read F for ever when you fill up, and then drop quickly to E. I wanted a better solution.

Bending the control rods on the senders would simply amplify the problem, so I thought that an electrical solution would be best.

What is needed is a solution that does not affect the F end of the scale at all, while allowing an adjustment to the E end of things. Well, it turns out that this is VERY easy and cheap to do. Please refer to Figure 1, You will notice that we have the AWD circuit diagramed here. If you follow the path of electricity from the battery, through the guage, through both senders, and to ground, you will notice that the more electricity flows through the senders, the higher the neele in the guage reads. The less that flows the lower it reads. For those of you non-electronics people out there, think of the wires as a pipe, and the two senders as valves. The "water" flows in through the top, through our "Water meter" and through both valves before exiting. If we shut off the valves a bit, the "water meter" will show less water flow (current). Now, when both valves are open (low resistance - full gas tank) the water flow meter reads high. When both are nearly closed (high resistance - empth gas tank) the water flow meter reads low.

Our problem is that when both valves (senders) are in their highest resistance state (tank empty) the water meter is not reading enough current flow. This is the fix - we create a leak before the pair of senders. Put a small hole in the pipe, so now more current can pass the meter, which will cause it to read lower, and more accurately represent the amount of fuel in the tank (none).

In reality what we do is to wire a small "variable resistor" between the power wire from the guage to the sender, and connect the other end to ground. This allows MORE current to flow through the guage, and gives it a place to go (to ground).

Figure 1(Click on Link): Here's the schematics I created for the Fuel system on the 2G AWD DSM cars. Project details are at the bottom. Sorry these are so big, but that's so you can see what I'm talking about.

Now, on to the project.

Here's the 'Project' Part, if you can even call it that. Materials required: Soldering iron, solder, 1000 Ohm (1K Ohm) trimmer pot, 2' of wire, 2 "Scotch lock" wire tap connectors (RS #64-3052, $1.69 for 10).

Remove the back bottom seat from the car. (Pull tabs and lift) Under the passenger side you will find a small metal "door" and a white wire loom going to it. Unscrew the white wire loom cover and untape it from the wires. Locate the YELLOW (no stripes, just little silver tick marks) wire, and the thick black wire. Now, go inside and assemble your fuel tank adjuster as shown below.

Cut or break off the last terminal, solder one foot wires to the other two. Cover everything with electrical tape, and leave the screw sticking out. Connect one end to the yellow wire in the car, and the other to the thick black one. DON'T cut the wires in the car, simply splice into them with the scotch locks. (wire taps)

Reassemble the wire loom guard, but leave your adjuster hanging out into the rear seat footwell. (You will need to adjust it).

Now, to adjust it you MUST run the car out of gas. People have asked a zillion times for a "magic number". Well, there isn't one. The guage is finicky and each car I have done is somewhat different. I suggest doing this mod when you are already close to running out (light has been on for at least 20 miles or more).

Now, put a 1gallon gas can in your trunk ($4 at K-Mart) with a gallon of gas in it. And drive until you feel the car running out (you'll know). Once it starts to stumble (usually around a right hand curve or up a hill) pull over and shut it off. (try to park in a fairly level area) Turn it back ON, but don't start it. Now, get out a small screwdriver (you DID remember to bring it, right?) and turn the adjuster ONE TURN CW to raise the needle, CCW to lower it. YOU MUST WAIT AT LEAST 1 MINUTE FOR THE GUAGE TO REGISTER. Now repeat if necessary. I had to go 3-4 turns. Take your time!

Once you think you have got it where you want it (I put mine 1 needle below E) WAIT another couple minutes to be sure the guage is settled. Then get out and dump in your gallon of gas and go to a gas station.

You are finished! Once you have drived all the way to E and are happy with the results, tuck the adjuster up into the wire loom, tape it up, and you are done.

This is not my write up and I am in no way taking credit for it..

 

[96TSi_Chris]

Ive gone 40 miles after the light has been on before i got gas. So the 2-2.3 gallons left seems about right.

I get 23 mpg.

 

[CornerHard]

The light stays on at about 12 gallons used for me, and the 2G AWD tank holds 16 gallons according to the manual.

 

[90gs-turbo]

Well you guys are lucky my gas lite doesnt come on at all Ive been wondering about it latley ..When my arrow reads below -E- still no lite