I had somewhat the same problem a few years ago...put the car in the garage, did some work and then cranks but wont stat. If i rember well, i was not geting any fuel (or maybe spark?), anyways the car would run with the relay bridged, and after checking all the electrical (including the fusable link by the battery) it turns out to be the connection on the fire wall, on the passenger side where the positive witre runs from the rear of the car to the front, then splits to go to the starter and fuse box. Make sure that is clean and tight. Othere then that check the crank sensors, on the side of the trany, if one of them in gone the engine will rotate but not start...
Hope this helps!
Specialized in BMW recycling, all OEM used parts
Up to 90% off new cost!!!
Most models E30 E36 E46 E90 E92 E93 E34 E39 E60 E32 E38 E65 E66 X3 X5 M3 M5 Z4
2nd location opening SOON!!!!
Call 11-8PM 416 821-2578
New inventory daily. 50+ cars in stock!