Fuel is extremely flammable, so take extra precautions when working on any part of the fuel system. Do not smoke and do not allow open flames and lamps without shades to appear near the working area. Do not work in a garage with natural gas equipment (such as water heaters or clothes dryers) with wick. If fuel comes into contact with skin, wash immediately with soap and water. When doing any work on the fuel system, wear safety goggles and have a fire extinguisher ready.
1. Check the chassis wire connection. Check all cable connectors that are connected to the system. Loose connectors and bad connections to the chassis can cause many problems that lead to more serious problems.
2. Make sure the battery is fully charged, as the control unit and sensors require an uninterrupted power supply for proper fuel metering.
3. Check the air filter element - a dirty or partially clogged filter will greatly impair performance and economy (see chapter Car maintenance).
4. If a blown fuse is found, replace it and check if it has blown again. If so, look for a short-to-ground wire in the cable associated with the system.
5. Check for leaks in the intake duct from the air flow meter to the intake manifold. Also check up a condition of vacuum hoses suitable to the inlet pipeline.
6. Disconnect the intake air duct from the throttle body and check for dirt, carbon deposits and other deposits inside it. If dirty, clean it with carburetor cleaner and a toothbrush.
7. With the engine running, touch each injector in turn with a screwdriver or stethoscope and listen for clicks indicating operation.
8. Check the pressure in the fuel system (see Section Fuel/Fuel Pump Pressure Check).
9. If these checks fail to detect a malfunction, send the car to a BMW dealer who, using special equipment, will be able to read the trouble codes from the ECU memory.