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Low Fuel "red"light


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Is the light out of whack, or your fuel gauge? My gauge is starting to go wonky on me, especially when it's cold out, but the light is usually right on.

 

BTW: To measure the accuracy, wait until the light just comes on and fill your tank. Total capacity should be 15.9 gals, and the light comes on at 2.4. If you have to add somewhere around 13.5 gals, the light is correct.

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I have not actually looked into the problem, but here's what I think is going on:

 

The fuel light sensor is probably triggered by a microswitch on a rod with a float attached to it, and is either "on" or "off". I've been told that it's separate from the gauge sender, and a simple switch is probably cheaper than a variable resistor. So I don't think there's too much that can go awry with the light, aside from the rod getting bent or the pivot getting sticky.

 

The gauge should be controlled by a variable resistor with a float attached. When new, the change in resistance as the float moves is smooth and uniform. As they age, the resistance level overall can go up or down (more likely up) and the changes in resistance as the float moves can become less smooth. (My gauge tends to "stick" in some places and go down rapidly in others). Since a fuel gauge sender probably isn't cheap, I would recommend taking it out and cleaning up all the contacts and stuff, as that could be causing your issue here. (I can't justify spending the money on something like that for my car, but to each his own.)

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More theoretical ramblings:

 

I don't think you have to remove the tank, but I could be wrong. When I stripped my interior, I found a little removable plate in the floor right above the gas tank. I bet if you take that plate off, you can access the sensors and stuff through the floor.

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Would suspect the wiring harness connector also. Have had wonky gauge and fuel light on 2 of the BRATs. One was just corroded connector, other is bad sending unit. Also, the units "ground" thru the tank itself, if you lose the ground, they'll get weird on you. Bad ground can be fixed by running a screw thru the lip of the tank into the mounting area of the body, works most of the time anyways.

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  • 12 years later...

I'm new to this group and this is my first post. Even though this thread has been dormant for 12 years I decided to post here since I have a similar problem with my 84 GL wagon 4X4, EA82. Sometimes the car runs poorly, similar to a restricted exhaust or fuel starvation. The problem comes and goes. I can drive it for 30-40 miles with no problems. At other times it acts up after just 5-6 miles. I've checked for exhaust restrictions and replaced a double walled exhaust pipe that had separated, but wasn't collapsed. I have also verified adequate fuel volume and pressure to the carburetor, at least while idling in my driveway.. Yesterday it started running poorly after about 4 miles. At that point I noticed the low fuel light was on, even though I had close to a full tank of gas. Is it possible for that light to trigger something to make the fuel system "think" it's out of gas?

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Urabus84 wrote:

"Is it possible for that light to trigger something to make the fuel system "think" it's out of gas?"

 

No.  Nothing that fancy in there anywhere.

 

Fuel filters

pump

crud in the tank

other intermittent electric problem [in the ignition circuitry]

 

Best to start as new thread.

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