BMW E34 stalls while driving
Why does the E34 stall while driving?
Severe running trouble or stalling is usually caused by one of two things: fuel is not arriving (pump or relay), or the engine management is not getting information about engine rotation (crankshaft sensor). Check these first.
How does a fuel pump fault show up?
The engine stalls or loses power as it warms up, and the pump runs only occasionally. Fuel pressure can collapse below half a bar, at which point the engine stalls. A new pump fixed the symptoms in several cars.
Can the electrical system stall the car?
Yes. If the alternator does not charge, the battery drains, the ABS light comes on first and the car stalls. The main fuse can also be at its breaking point and cause confusing faults. Check the fuse and the oxidation of the grounds.
What if there is no spark but fuel is arriving?
Then the fault may be in the engine control unit or the crankshaft sensor. Without the sensor's signal the engine control unit gives neither fuel nor spark. If all the engine management relays click in unison, the cause is the engine control unit.