Fuel guage gives wrong readings

[Hugo]

My fuel guage gives me false reading after long trips once the fuel guage goes under half way. The next time I start the zed the fuel guage tells me I have a full tank and won't change until I put more petrol in but the guage goes down below halfway if I do short runs.

Is this a fault with z3s or do I need a new fuel pump with sender?

 

[hard top]

Fault with Z3's, they are notorious for that.
Have a read of this........ https://zroadster.org/articles/bmw-z3-fuel-sender-unit-removal-fix-your-faulty-fuel-guage.48/

 

[GazHyde]

Yeah, as Mike says pretty common and as you will see from the write up BMW conveniently put the access panel, in a fairly inaccessible location...