Finally got around to pulling out the fuel pump and gauge sender unit. it was not as a big a job as I imagined.
The float is freely moving and everything looks fine. Cleaned and lubed all moving parts and re-installed.
The gauge is still not working so expect that one of the electrical components may be stuffed. I did put a multimeter over the sender unit and moved the float up and down. I did see a change in resistance, but I don't know what it should actually be reading. There is a capacitor (or something) on the side of the sender unit, so I wonder if that could be stuffed?
Anyway, I will drag the car's sorry backside into an auto electricians this week for a closer look.
Meanwhile, the trip meter is a good indication of how much is remaining...
It seems to be averaging around 14litres per 100 km around town (aircon always on and in the tropics) - and yes it has been tuned and checked over!! - so when the car gets to around 400kms on a tank it is time to fill up.
Loving the old car experience! Have a good weekend all.