My 1985 e24 635csi hit a bump exiting freeway & cut off never to restart. #18 (fuel pump fuse) lights deem when tested. Fuel pump will not work unless relay is jumped, even then car won't start. I've read thread after thread after thread trying to solve this problem. Found a used ECU & Relay box (located under driver side dash), installed, no change. A few of the 7.5 fuses are not hot either. Changed every relay possible (which relays must I be careful changing? All the fours look alike 'not a good joke').
What else should I check? Turning on the ignition switch does ignite fuel pump. Read a post this morning about Crank Sensor & Speed Sensor, however my thinking is (would a sensor stop the fuel pump from working and, would a sensor make the fuel pump fuse go deem?). Could it be a bad ground wire? If so, where should my search begin?
In conclusion, I did have a music system installed one day previous to the car stopping. Not sure if this plays a role either.
I'm a new owner trying to have a good experience,