BMW 3 Series E30

since 1983-1994 release

Repair and operation of the car

+ 1. Maintenance instruction
+ 2. Maintenance
+ 3. Engine
+ 4. Cooling system
+ 5. Heating and ventilation
- 6. Fuel system
   6.2. Specifications
   6.3. Check of system of injection
   6.4. Air stream measuring instrument
   6.5. Throttle branch pipe
   6.6. Fuel pressure regulator
   6.7. Nozzle of launch of the cold engine and thermotimer
   6.8. Check and replacement of nozzles
   6.9. Air proofreader of idling
   6.10. Order of a decompression of fuel system
   6.11. Check of pressure of fuel
   6.12. The fuel pump, pump of pumping and the fuel level sensor in a tank
   6.13. Fuel pipes and union
   6.14. Fuel tank
   6.15. Air filter
   6.16. Cable of the drive of a butterfly valve
   6.17. Carburetor
+ 7. Exhaust system
+ 8. Transmissions
+ 9. Coupling
+ 10. Brake system
+ 11. Running gear
+ 12. Body
+ 13. Electric equipment
+ 14. Useful tips


6. Fuel system

6.1. Introduction


The considered cars are equipped with system of injection of fuel, except models 316 on which Solex 2B4 carburetors (cars of early release) of and Solex 2BE (later release) are installed. The fuel pump of carburetor engines mechanical, with the cam drive from a cam-shaft.

System of injection like L-Jetronic or Motronic. Since 1988 cars are equipped with the advanced Motronic system in which there is no nozzle for launch of the cold engine. The electric fuel pump is mounted or in a back part of the car, on the body bottom (on early models), or in the fuel tank. In the Motronic system of the relay of injection works from a signal from the control unit (ECU block). At inclusion of ignition the fuel pump works within several seconds and is switched-off only after a full stop of the engine. On early models the pump of pumping of low pressure mounted in the fuel tank and which is switched on consistently with the main pump is provided. The main pump provides maintenance of necessary pressure of fuel. Maintenance of constant pressure at the time of injection is provided with the regulator of pressure and a suppressor of pulsations of pressure (last is mounted about the fuel filter).

The system of injection of fuel of the considered cars consists of 3 subsystems – fuel, an intake of air and the processor control unit.

Fuel system

The fuel pump provides supply of fuel via the filter in the distributor under constant pressure. Stabilization of pressure of fuel at the exit of the distributor is provided with pressure regulator.

System of an intake of air

Consists of the air cleaner, measuring instrument of a stream of air, throttle branch pipe, soaking-up collector and the connecting hoses and branch pipes. The measuring instrument of a stream of air of bladed type, consumption of air is proportional to the angle of rotation of the gate and resistance of a potentiometer which are rigidly connected with a gate axis.

Electronic control unit

On the car the electronic control unit (ECU) which provides automatic adjustment of the moment of ignition and also quantity and composition of fuel-air mix according to information from various sensors tracing power setting is established. The structure of auxiliary elements of system (sensors, switches, etc.) is defined by a concrete type of the applied system of injection.

The applied systems of injection

System of injection like L-Jetronic of Bosch (till 1987)

System of injection L-Jetronic
1. Fuel tank
2. Rapredelitel of fuel
3. Pressure regulator
4. Processor block
5. Relay
6. Stream speed measuring instrument
7. Ignition switch
8. Battery
9. Butterfly valve
10. Switch of a butterfly valve
11. Valve of start of the cold engine
12. Proofreader of idling
13. Ignition distributor
14. Thermotimer
15. Engine temperature sensor
16. Oxygen sensor
17. Nozzle
18. Fuel фильт
19. Fuel pump

System odnoforsunochny with an electromagnetic nozzle. The basic adjustable parameters are duration of an open condition of nozzles (amount of injectable fuel) and idling turns. Auxiliary elements of system are the sensor of temperature of cooling liquid, switch of a butterfly valve, idling stabilizer (perepuskny the air valve), relay and safety locks.

System of injection like Motronic

System of injection Motronic
1. Fuel tank
2. Processor block
3. Quencher of pulsations
4. Fuel pressure regulator
5. Valve of start of the cold engine
6. Switch of a butterfly valve
7. Stream speed measuring instrument
8. Proofreader of idling
9. Relay of the fuel pump
10. Main relay
11. Ignition switch
12. Battery
13. Sensor of an angle of rotation of the crankshaft
14. Butterfly valve
15. Sensor of speed of rotation of the crankshaft
16. Engine temperature sensor
17. Thermotimer
18. Oxygen sensor
19. Ignition coil
20. Candle
21. Nozzle
22. Ignition distributor
23. Fuel pump
24. Fuel filter
25. Fuel distributor

System mnogoforsunochny with electromagnetic nozzles. Adjustable parameters are the amount of injectable fuel, ignition moment, turns of idling and composition of exhaust gases.