Yak-1 fuel gauge don´t work

[E69Evil_Elvis]

At some point I can see a flicker with what I think may be the true reading, but almost always shows the fuel tank full, even without loading the full load.

[coconut]

At some point I can see a flicker with what I think may be the true reading, but almost always shows the fuel tank full, even without loading the full load.

 

There are two gauges, located on the wings. They only show the last 80 liters in each wing. Are these the gauges you are looking at?

[E69Evil_Elvis]

Yes, just those. 

[ShamrockOneFive]

The key thing is that they will show a full load until you're under the maximum reading. Then they will begin to show the amount remaining. Until then its full. It's a quirk of the aircraft.