Diesel fuel gauge erratic/fauly?

[grivas]

Today I went for a drive with my wife and I was aware that I had a little over a quarter of a tank full of diesel as indicated by the gauge, but about a couple of miles of travel and I noticed the low fuel warning light come on and the gauge needle had dropped to less than an 1/8th or less full indicated, as I was near an Esso station I decided to fuel up, so I stopped and put in 20 litres where upon the gauge needle moved to 3/4 full. On our way back home, approx. 35 miles later I stopped at Sainsbury's for some shopping and decided to top up the fuel, but I was only able to put in a further 16 liters approx. before the tank was brimmed, what I don't understand is if the tank has a 65 litre capacity, the warning light should not have come on when it did as I would have had at least 30 litres in the tank at the time the warning light illuminated, at least that is what I estimate.
What is happening?, I do know the gauge in these cars is stupidly inaccurate?, any ideas?.

[Robson Rover Repair]

Probably find the sender has jammed on one side. Or if you had an intank pump recently done it was twisted then.

I once owned a 75 owned by a ham fister owner who had changed the intank pump so badly, that when you put in as little as 5 litres from the red light being on the car was convinced you where almost full.

I must admit I drop it for a few years and after running out a few times I eventually ripped the whole lot out, tank and all, and did a full replacement of everything properly to get it right.

12 years later the cars still on the road in Basingstoke now.

[grivas]

Thanks for the reply, I haven't had a new pump fitted and I can't understand how the sender could have got stuck, can it be unstuck without taking the whole thing apart?

[grivas]

I have just taken some readings using the diagnostics tool and these are :
--6.0 --0570
--6.1 -----
1-6.2 --0570

Now I am not sure how to interpret these , but it appears that one of the sensors might be malfunctioning?, so if anyone has any ideas please explain. Thanks

[grivas]

I also understand that there was some discussion regarding a 'software reset' within the diagnostics package which in at least one case has been successful in curing the erratic behaviour of the fuel gauge.
Does anyone have any recent experience with this or any other information, I understand that member T-cut has some knowledge and/or experience in this?.
Please help if possible, thanks.

[grivas]

Final plea for any useful information on this subject, all the search carried out leads to either inconclusive solutions, or solutions where no detailed information is offered by people who managed to successfully solve the issue, missing photos make matters worse.
Anyway thanks to those who have taken the time to offer some suggestions.