Sounds like a typical failing fuel pump. You can try to "jolt" it back to life by lifting up the bottom cushion of your backseat (if just snaps into place), then pull back the insulating fabric, and then remove the passenger side metal cover that conceals your fuel pump. Tap on the top of the pump with a non-sparking object, being careful to not hit the electrical connector. (it will break). Try to start the car. If it doesn't work after a few light taps, hit it a bit harder and try again. If the car starts, you'll be needing to replace the fuel pump very soon. If it doesn't start, you can also try tapping the primary fuel pump which is located beneath your car near the back left tire. (early e30's had a "lift" pump beneath the seat and a primary high pressure pump near the tire). If tapping doesn't work, check fuses and fuel pump relays. Some would say check the electricals first but this is such a common problem in older e30's and a dead or dying pump is usually the culprit.