[megadamp]

I fill up with texico to the first click. Gauge goes to full. Works reasonably well apart from the odd on kerb or uneaven ground issues, but not to bad soon settles once on the move. Part fill with 20 litres or so of fuel. readings go all over the place.
If on a downward hill goes to zoro. On the flat can't be relied upon. Is it the instrument cluster calc algo going bonkers?.
Tried all the fuse pulling and disconnect of the harness.

 

[rocketman4321]

It could be the sender unit, just like the old-fashioned ones that didn't need software! There's a wiper over a coil in the sender attached to the fuel pump. The wires can get cruddy, corroded, or the wiper arm can break. Some folks have had luck cleaning it with a pencil eraser and contact cleaner, but I had to replace mine (requires the whole pump assembly). Works fine now.
I don't know how to tell this problem from the algorithm one--but I tried numerous resets/fuse pulls before I gave up. But it's pretty simple--if the gauge sinks to zero, the wiper's on a dead spot.

 

[megadamp]

Ok cheers, looks like i need to pull it out and see if it can be cleaned.

 

[Noodles]

I have to do the same thing. I did a an instrument cluster test when I checked the MIL light in that thread.
The SDS tested all gauges and the fuel level rose from top to bottom as it should.
Mine read empty after a fill and then at about 70% of a tank it starts to work again.

 

[megadamp]

Hi Noodles did you just clean the contacts or renew?. Sorry re-read. Are you saying yours is up and down aswell. Its just funny how a top up will cause it to loose its acuracy.
I have used texico fuel as i think in the uk it has techron additive in it, and it does without question help with fuel gauge varnish removal. I have tried to keep it reasonably full to get it to work on the sender as techron additive in the uk is as rare as rocking horse shit.

 

[Noodles]

I still have to take my pump out try to clean it. Should get to it in a week or two.

As of right now it is giving goofy readings. It does not start working until a little under 3/4 of a tank.