The low fuel level light comes on in my car when the tank is 3/4 full. I know this is a minor annoyance, but does anyone know what could be causing it?
Low fuel level light?
The low fuel level light comes on in my car when the tank is 3/4 full. I know this is a minor annoyance, but does anyone know what could be causing it?
Is the gauge also off?
A tale of 2 foxes,
my 86 mustang the light comes on at 1/4 tank.
My 84 Capri at empty. I figure with each I have about 50 miles
to get gas or start walking.
My guess is the float or the float arm has an issue.
What does the gauge read when empty?
Ray
86 Mustang LX 3.8 Convertible (bought new}
65 Galaxie 500 XL 390 auto
2A
This subject is interesting to me also because my cars low fuel light started to act up last year. It started to come on when the tank was obviously not empty
Tony
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Mine has been doing that every now and then for many years.
Low fuel light comes on when there is plenty of fuel.
No pattern. Month, weeks, weather.
Otherwise the fuel light works normally.
On at about 1/4-1/8 tank. Gal or 2 left. Time to get some fuel.
i open the glove box
reach up inside and gently wiggle the wires behind the pass side dash panel.
Directly above center to left of center of glove box opening near the box light switch.
Wiggle until light goes out.
Takes couple seconds and works every time.
Occasionally have to repeat this again within a couple of minutes then its fine.
It is one wire doing this. Cannot see where it goes.
Guess is some kind of minor wire connection problem at the low fuel sensor unit connector mounted up there.
Nothing i want to fool with trying to guess fix an good old intact inaccessible harness making things worse.
Last edited by gr79; 06-03-2017 at 09:58 AM.
An issue with the float or float arm would also cause the gauge to read inaccurately. If it was a sending unit issue then theoretically both the gauge and low fuel light should be wrong, but just as wrong as each other. On mine I decided I wanted the low fuel light to turn on sooner (easier on the pump, and I never trust these gauges), so I bent the float arm slightly before installing my new sending unit (the float fell off the arm, annoying problem to have). It causes the low fuel light to turn on 1-1.5 gallons sooner, but also causes my gauge to be buried on full for a very long time.
we bent it up. This caused the pickup to read less full with a given fuel level.
The reason the gauge stays full so long is the odd shape of the tank combined with where the the pickup is. You can't accurately measure N inches of fuel with a gauge pickup stroke that is N-3. Therefore full forever then falls pretty fast.
I suggest removing and cleaning the wires where the harness connects to the sending unit and also where the harness connects to the body harness. "Bulb" grease (di-electric grease) is helpful for ensuring a good connection. You also want to secure these wires as moving around will cause them to break down over time.
Last edited by erratic50; 07-06-2017 at 10:40 AM.
Just chiming in here as well, my 79' shows the low fuel light any time that there's less than 3/4 tank or so, but I have had it come on within minutes of leaving the gas station.
What actually causes the light to illuminate? is it resistance based somehow?
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