If your 2004 BMW 645 cranks but won't start while the crankshaft pulley moves, it typically indicates that the engine is attempting to start but is not igniting the fuel-air mixture. This could be due to several issues, including a faulty fuel pump, clogged fuel filter, ignition system problems, or issues with the engine's sensors. It's essential to check for error codes and inspect the fuel and ignition systems to diagnose the problem accurately. If you're unsure, consulting a professional mechanic is recommended for a thorough evaluation.
Engine cranks but doesn't start.
check the crankshaft sensor
its not your ignition its your crankshaft sensor that's the same problem i had.
To change a crankshaft pulley, start by disconnecting the battery and removing any components obstructing access, such as the serpentine belt and protective covers. Use a crankshaft pulley puller to safely detach the old pulley. Once removed, clean the crankshaft end, then align and install the new pulley, ensuring it is securely fastened. Finally, reassemble any removed parts and reconnect the battery.
Crankshaft position sensor.
I say try changing out the crankshaft sensor.
To remove the crankshaft pulley from a Vauxhall Corsa, start by disconnecting the battery and removing any components obstructing access to the pulley, such as the serpentine belt. Use a suitable socket to loosen the crankshaft pulley bolt, which may require a breaker bar for added leverage. Once the bolt is removed, you can use a puller tool to gently detach the pulley from the crankshaft. Be sure to follow any specific guidelines for your vehicle model to avoid damage.
If this is a Power Stroke engine, the most likely cause is a faulty crankshaft position sensor.
Some possible problems when your vehicle cranks, but won't start are a bad crankshaft position sensor, or a faulty ignition switch. Another possibility is a loose or broken wire that runs from the sensor to the PCM.
timing chain or gear is broken thats why it cranks so fast the starter is just turning the crankshaft not the cam. look or feel the rocker arms if they are not moveing its the the timing belt/chain
do you mean it cranks, but will not start?
check your battery or you spark plugs