Fuel Injection Power Systems: Operation and Types

Issue 31: Fuel Injection Power Systems

Food for Fuel Injection

This system supplies power to the combustion engine, replacing the carburetor with a system that injects gasoline directly into the air intake. Advantages of fuel injection systems:

• High performance
• Less fuel consumption
• Fast adaptation
• Reduced pollutants

Injection can be direct or indirect. Direct injection sprays fuel directly into the cylinder, maximizing engine power but requiring higher pressure. Indirect injection sprays gasoline into the intake manifold, with a simpler installation due to lower pressure requirements. Injection can also be continuous or discontinuous.

Mechanical Fuel Injection

Mechanical injection systems are powered by the internal combustion engine or lack an actuator. Engine-driven systems use an injection pump with a regulator, similar to diesel engines. Alternatively, some systems operate by injecting continuously without an actuator.

Electronic Fuel Injection (Fig. 11)

Electronic fuel injection systems offer high sensitivity, providing the appropriate fuel level to the cylinders at all times without needing a high-precision mechanical distributor. The L-Jetronic system by BOSCH is a discontinuous, multi-point injection system.

System Elements:

• D - Fuel Tank
• O - Air Flow Meter
• B - Fuel Pump
• C - Intake Collector
• X - Fuel Filter
• A - Intake Tube
• Z - Fuel Distributor
• E - Control Unit
• R - Pressure Regulator
• L - Lambda Probe
• N - Cold Start Valve
• V - Thermo-Timed Switch
• F - Passivity Film Filter

The fuel injection system delivers the exact amount of fuel needed based on engine requirements. Sensors record data, which is converted into electrical signals and processed by the control unit to adjust fuel flow.

Working Principle

A pump (B) draws fuel from the tank (D) and pressurizes the fuel distributor pipe (Z). Injection valves (V) inject fuel into the intake pipes, controlled by an electronic unit (E).

Functional Blocks

The L-Jetronic system includes the suction system, sensors, control unit, and power system.

Power System

The power system delivers fuel from the tank (D) to the injection valves (V), maintaining constant pressure. It includes the fuel pump (B), fuel filter (X), distributor tube (Z), pressure regulator (R), injection valves (V), and cold start valve (N).

Catalytic Converter (Fig. 13)

Gasoline combustion is often incomplete, producing harmful emissions like carbon monoxide (CO), nitrogen oxides (NO), and hydrocarbons (HC). The catalytic converter transforms these into harmless components using platinum and rhodium.

Two-Way Catalytic Converter

Uses platinum and palladium to eliminate carbon monoxide and hydrocarbons, converting them into carbon dioxide, water vapor, and nitrogen.

Three-Way Catalytic Converter

Adds rhodium to reduce nitrogen oxides into nitrogen and oxygen. Used with electronic injection systems having a lambda probe.

Vehicle Considerations with Catalytic Converters

• Do not use leaded gasoline.
• Oil consumption should not exceed one liter per 1000 km.
• Avoid short trips with a cold engine.
• Do not push-start the vehicle, especially when warm.
• Avoid additives containing lead.
• Check engine tuning regularly.
• Avoid frequently running on a reserve tank.

Maintenance and Adjustment

Follow manufacturer instructions for power system maintenance. Expert diagnosis, testing, and tuning are essential for carburetor or injection systems.