Fuel warning light

[31449]

I have recently refitted my fuel system on my 1971 stag and now the fuel light on the dashboard cluster is on all the time. There is plenty of fuel in the tank and the fuel gauge is reading half full.
Any thoughts on the matter would be appreciated.

[richardthestag]

the low fuel warning light is controlled by the float level sender in the top of the tank.

Green / Orange wire if I recall correctly, the other wire is for the gauge. Swap the two wires around maybe you fitted them the wrong way around. Else you need to remove the tank sender and bench test it

[31449]

Will change wires and let you know ,thanks

[Philip Wardle]

The sender has three terminals of which the earth tag is fairly obvious, the other two are identified by the letters "W" and "T" which are stamped adjacent, although these are often difficult to see owing to corrosion. The green/orange wire goes to one side of the warning light, and the other side of the warning light goes to + 12V. The fuel level switch in the sender is open until the fuel level becomes low, at which point it closes and connects the "W" terminal to ground. This complete the circuit for the warnng light, which now turns on (but may well flash on and off while driving as the fuel sloshes around in the tank until the fuel level goes down a bit further).

So if you connect a jumper lead between "W" and the earth tag on the sender you'll be simulating the action of the level switch closing. If the warning light was previously off but now illuminates the fault is likely to be the fuel level switch in the sender. If the warning light does not illuminate the fault is likely to be a blown bulb or faulty wiring / dirty connector.

[31449]

Thanks for the info Philip will test today , Monday , and let you know.

[31449]

Have changed wires round and light still on but fuel gauge registers full. Have shorted to earth and no change fuel light on dashboard cluster is still on ..

[Philip Wardle]

The baseline situation is green/orange goes to "W", green/black goes to "T", the "GND" terminal goes to the chassis somewhere. The warning light remains off until either (a) the fuel level is low enough to close the normally open switch in the sender, or (b) you attach a test jumper between "W" and "GND". The fuel gauge shows the level in the tank depending on the variable resistance between "T" and "GND". Are the connections correct as in this picture?

IMG_4957.jpg

[richardthestag]

if wiring is correct, disconnect the green/orange wire at the tank, does the light go off? ground the green/orange wire to earth/ground wire. does the light go on?

if so the circuit is working, the fault may lay in your sender unit

[jbuckl]

Good info here

[sujitroy]

I had a problem with a leaking float and the gauge would not read full when the tank was full to the brim. Here a long video I made which may be of help: https://youtu.be/qTeskM6zDWo