E36 Fuel Level sender

[ScottyWM]

The fuel gauge in the E36 has started to go . It's the car my daughter drives, so I need to fix it. It will drastically drop from the 1/4 mark to empty all at once. Always from the 1/4 mark, never when it is fuller. And not every time, but most times. I'm assuming that the fuel level sensor is either hanging up or just plain gone bad. Turns out there are two sensors, one on the pump and one on the other side of the tank.

Couple of questions...
1) Does this sound like a bad sensor or could it be something else? I've got the bently manual, so I will be able to check their resistance once I get them out, but I'd like to know before I tear it apart - so I can order parts and have them ready to swap out. (But how would I know if I needed the cheap sensor or the expensive one on the Pump?)

2) Is this something I can safely do myself? It involves working around gas after all. It's funny, the Bently manual says to empty the tank first - but the instructions on emptying the tank say to empty it from the openings where you remove these sensors. Would it be safe enough to just do the job when the tank is running on low anyway? (Yes, disconnect the battery first!)

Thanks guys, I would assume any t-shooting for this would be pretty much the same as on the E34 - so let me know if you have any insights.

[shogun]

maybe this helps
http://www.pelicanparts.com/BMW/tech...-Fuel-Pump.htm

more here http://www.pelicanparts.com/BMW/tech.../tech_main.htm