when does the low fuel warning light kick in? '82 GSA

[sonoramicommando]

It seems the fuel gauge calibration is a bit off, I just filled up and it took 36 litres and that's from the gauge reading empty. The owner's manual says the tank holds 43 litres so I have 7 litres to go empty.
That got me curious - when does (or is supposed to) the low fuel warning light come on? I hope this is not tied to the fuel gauge. I think I have checked the bulb but since then the car has developed some earth problem and fuel gauge and trip meter lights only come on intermittently when head lights are on.
Cheers,
Sam

[Stonehopper]

Good question. I don't know, it could be triggered by the gauge needle, and I do know my GS would read three quarters of a tank when filled to the brim - but - a) there's no low fuel light, and - b) I fixed that by bending the gauge needle.

Pop up menus - get rid of one and another appears . . . !

[sonoramicommando]

Hmmm - I'll try to find out this weekend. Going on a (relatively) long open road journey... I should carry a spare fuel can, just in case...

[sonoramicommando]

Well - it does work, but not sure exactly when it kicks in as it seems to be suffering from intermittent ground fault.
At standing still, the light came on steady with ~6 litre left but it goes out when moving.
I'll have to try again when I'm back on the usual commuting route - just did ~400km open road trip this weekend. I should have brought earplugs with me =)