HOW TO drain fuel from1985 535 bmw

Option 1) Use a fuel siphon to remove it. It would be a good idea to change the fuel filter which could be very clogged up and might not allow enough fuel to get to the engine. Option 2) If you find where the fuel pump is located, you could access the fuel tank directly through there and remove most of it as well. Option 3) You might want to remove the fuel tank altogether if it's been sitting for a long time and the fuel has turned to varnish. Make sure you do this work in a very well ventilated area and do not smoke or make any sort of sparks!!! It's the fumes that are very volatile. You should do more research by searching the internet and use the various BMW forums. Lots of good info in them provided by enthusiasts.