Fuel Gauge Accuracy

[bhartman]

I have severe doubts about the accuracy of my fuel gauge, but the dealer says there isn't a problem.

When I went on my first road trip, I was watching the fuel gauge and comparing it to the odometer. (Various reviews had said that the Cobra's fuel mileage was very poor.) At 1/2 tank I was thinking, "Man, I'm getting great mileage! I've travelled almost 200 miles!"

Lucky for me I decided to take a break and fill the tank up! With the fuel gauge at 1/2 tank, I was able to put in 12 gallons!

Let's see... 15 gallon tank and at 1/2 tank I only had 3 gallons left. Doesn't seem right to me.

Has anyone else experieneced this problem?

[trmn8tr]

I can't think of a Ford vehicle that I have driven in the past 25 years, and there has been plenty, that didn't do this to some degree. Seems Fords always get more out of the first half than the last, mine stays on full forever and then drops like a rocket once below half full. At an indicated half full on the gauge she will take about ten gallons, not quite as extreme as yours is doing but I wouldn't worry about it, just note it and refill accordingly.

[Waltman]

The needle doesn't seem to be accurate, however, the fuel warning light seems to do a better job. I'd noticed that after driving I see the needle, let's say in the middle (half tank) position, then next morning comes, the needle is like over a 1/4 tank less!, like someone stole gas?? Weird :huh:

I usually drive until the needle is ON the red, that means a little over a galon left. Doing freeway (90%) I get so far 250 miles per 14 gallons. A combination of 60% freeway, 40% traffic, I get around 210 miles per 14 gallons. SOOOO, as soon as I see 200 miles in the tripmeter or close to it, I start looking for the nearest gas pump.

With Mustangs, you better go by the odometer, reset it, every time you fuel up, get to know your beast, and feed it when HUNGRY :D

[counihan]

Fuel gauges either work or they don't. Our 97 GMC Jimmy and other GMC units with the same fuel tank float/assembly unit are notorious; had it replaced 3 times, but we still go by the trip odometer. My 03 Cobra seems to behave well so far. Mfgrs tend to try to set up new gauging assemblies to preclude owners from running a tank dry and hence burning up the electric fuel pump. Sorry I can't add any other concrete suggestions beyond those others have already stated...especially using the trip odo. I know that isn't too great either, since my fuel mileage has varied between 12 and 23 depending on the position of my foot on the throttle... Hey, Walt, nice redfire...similar redfire from Kern County.

[spiced]

Interesting. My 03 Cobra stays at Full for about 40 miles when it gets to Empty it takes about 13 gallons. :huh:

[RingTheory]

I usually do not let my gas meter go below 1/4 tank, but I have noticed that it sits on the full line for a conspicuous length of miles. My mpg's has remained a constant 11.6mpg since I have been monitoring it using the trip odo and the gas fill. That is better than the 9.2mpg I was getting with the stock exhaust. My rpms spend most of their time between 3K and 4K. I was able to get 23 mpgs when I kept the rpms lower than 3K.

[krman68]

I agree with you Spiced

The most I've been able to put in is 14.1 gallons when the needle was below E. For a 15.7 gallon tank, where the heck is that fuel (1.6 gallons) hiding. My 1995 GT is the same way. It almost seems like the tank is smaller than 15.7 gallons.

[spiced]

When my dad buys a car he carries a half gallon of gas and runs the tank dry. Puts the gas in drives to the gas station and fills up. Then he know within a quart or so how much gas there is. I haven't done that on my Cobra but I figure when I'm on E there is still about a gallon or so in the tank. But next fillup maybe I'll give it a shot. If your going to try it just make sure as soon as the motor starts to stall pull over and put the gas in. Running the pump with no gas could burn it up and if you get air in the injectors it could make it real hard to start.

[davideast]

There is a way to read the fuel level digitally. See the "Gauge Codes????" thread and one of the codes is the fuel gauge digital input. The anolog gauge on the dash has a filter on it so it doesn't bounce around like the fuel in the tank. The digital reading bounces around but you can get a feel for the level by averaging it in your head. Go to the links that the thread indicates to find the "Gauge codes" and how to display it. The digital signal records levels between 000 and 255 where any thing below 054 (I think) turns on the low fuel light.

I think this will come in handy for the strip. Next trip I will run the 93 octane down until almost 000 level before I pour in the 104 Octane a gallon at a time so not to waste any.

Later