Inaccurate fuel gauge

[pogweasel]

Symptoms:

Fuel gauge under-reads. Anything below half a tank just registers as zero. Occasionally seems to read right but will then settle back either to nothing or a fraction of what is actually there.

Reserve light appears to be functioning correctly.

Is this a sender issue or something else?

Car is an '89 325i Touring.

Thanks

[TRANSPORTER]

What it might be is the small bolt behind the gauge itself, you will have to take out your instrument cluster quite an easy job I had mine out last weekend, and there is a thread on the forum of how to do it, wish I could give you the link but dont know how to sorry, anyway what you will have to do is tighten up the small bolt on the gauge, it gives a bad earth if loose hence giving bad readings, give it a go.