Erratic fuel gauge readings

[Martin15]

Erratic fuel gauge reading
Postby Martin15 » Tue Aug 25, 2020 5:26 pm
This post was originally placed under fuel systems, but I am reposting it here in hope of reaching a larger audience.
I am getting some very odd readings from the fuel gauge on my STR. Sometimes the gauge reads OK (in line with the range indication) Other time the guage can read completely off the scale and point towards 6 oclock. The range indicator remains correct. It recorrects itself occaisionally and works OK for a while, then goes whacky again. Any thoughts on what is wrong?
Thanks

[jeff1954]

Bad earth wire or dodgy sender unit maybe.

Jeff

[Martin15]

Thanks for your thoughts Jeff.
I have looked at and checcked the obvious earth points, without success. That doesn't mean it is not still the problem. I am told that Typpe R models have two tanks and the sender unit ballances the levels of both tanks for the gauge. Quite expensive to replace, so I am looking for any other alternative fixes before I go down that route. Car is furlowed for the winter now, so not so much activity until spring. I am hoping this mail mat spark some more thoughts.
Martin

[Martin15]

After a lot of researching forums, it appears that the root of this problem lays in the insturument binnacle. The only solution is to replace the complete gauge assembly, An enormous cost for just a faulty fuel gauge. There is a company in the USA who can repair gauges by fitting a new step motor, but this reuuires sending the complete gauge assy to them for the work to be carried out. Clearly this means laying up the vehicle for an indetirminate time whilst the work is done. Then there is the risk of what happens if the vehicle doed not start. So a new unit it is I guess.
Two main issues here.
1) The instrument assy form part of the vehicle security system and once removed and replaced, the vehicle will not start until it has been re-initialised using a Jaguar special tool.
2) New speedo is at zero and I would prefer it to reflect the actual milage of the car. Zeroed odometers always create suspicion regardless of any documentry evidence. Does anyone know of a legitimate service to install the correct odometer reading to a new instrument assy.
Looking for any information that may help.
Martin