BMW E34 will not start although the starter turns: crankshaft sensor
E34 cranks but will not start - can the cause be the crankshaft sensor?
Yes. When the crankshaft position sensor fails, the engine management does not give power to the fuel pump and there is usually no spark. If there is spark, the sensor is usually fine. Start the troubleshooting with this sensor.
How do I check the crankshaft sensor?
Measure the sensor's resistance between pins 1 and 2: the value is about 540 ohms +/-10%. The air gap between the sensor and the tooth is 1 mm +/-0.3 mm. Also check the connector and wires. All checks related to the alarm or anti-theft system are done with a diagnostic tool.
Can the crankshaft sensor work only partially?
Yes. An incipient fault shows up as long cranking times, random stalling or the car starting sometimes and not at other times. The cause can be the sensor, the connector or the wiring. A fault in the camshaft sensor usually does not prevent starting, but starting may take longer.
What else should I check if the sensor is fine?
Typical causes are the fuel pump or its relay, rust-clogged fuel lines and old petrol. A no-start can also be caused by a worn or damaged ignition component. Replace parts only after measuring, so you do not replace them needlessly.