Fuel System Safety
- Working on this fuel system is only permitted after the engine has cooled down. The coolant temperature must not exceed 40°C. This must be observed without fail, otherwise there is a danger of fuel sprayback on account of the residual pressure in the high pressure system.
- When working on the high pressure fuel system, take particular care to ensure conditions of absolute cleanliness and follow the work sequences described in the repair instructions. Even the tiniest contaminants and damage to the screw connections on the high pressure lines can cause leaks.
- When working on the fuel system of the N63 engine, it is important to ensure that the ignition coils are not fouled by fuel. The resistance of the silicone material is significantly reduced by heavy fuel contact. This can cause sparkover at the spark-plug head and cause misfires.
- Before making modifications to the fuel system, remove the ignition coils without fail and protect the spark-plug slot against the ingress of fuel with a cloth.
- Before refitting the piezo-injector, remove the ignition coils and ensure conditions of absolute cleanliness.
- Ignition coils heavily fouled by fuel must be replaced.
Scheme 951
Note. Do not open fuel lines until the coolant temperature has cooled to below 40 degrees Celsius (104 degrees Fahrenheit).