Fuel Gauge

My 2001 BMW 325i is having a few issues. My fuel gauge shows that I am always on empty to quarter of a tank even though the tank is full. I am having to go by the digital fuel gauge that tells me how many miles until I need to fill up. Does anyone know how to fix this?

I would suspect the fuel sending unit, locted in the tank. Check realoem.com for where she is located.

AutoZone has a good tutorial on their website for the R&R of your cars sender and fuel pump, just click on the repair guides and go from there.

They are easy to change. Remove the rear seat cushion exposing removable metal plates covering the top of the fuel tanks. Once you get these off, disconnect the electrical connectors & fuel lines & grab a giant set of Channel locks & unscrew the lock ring. R&R the unit & reassemble. 20 min job tops! Just do it when you have less than a 1/2 a tank of fuel as the old unit won't tend to drip fuel as much. The last sender I bought from the dealer for my E36 was around $60. Have fun as this is an easy job.

Not as much fun as my '88 750il where you have to reach down into the fuel and un-clip the pump assembly from the bottom of the tank to get the sending unit out for replacement.

Her is a good diy link. Follow the steps for the level sensor.
http://forum.e46fanatics.com/showthread.php?t=592414&highlight=diy

Before taking out the fuel sender (2 off) disconnect the connection and check the resistance at the terminals. Empty tank reads 10 ohms, half tank about 130 ohms and full 200 + ohms. Each sender should have comparable ohm readings. If not there is a fault in one sender. If the fuel gauge reads zero with the red light on indicating low fuel level, then bridge across the sender connection simulating full tank if no change then fault is in wire, computer or gauge, not senders.

Thanks for the link. I was searching for the same thing.