Many people are still unfamiliar with the term EFI or Electronic Fuel Injection. This term often appears in the automotive world. EFI itself is a series of electronic fuel supply systems. The EFI fuel system is believed to be able to mix fuel using a more accurate volume. 

Principle of EFI System Operation

1. When the Ignition Key is in the “ON” Position

For motor vehicles that use the injection or EFI system, this can be seen when the ignition key is still in the “ON” position. At that time, the electrical system in a car will be activated immediately with the main relay being connected. Then the ECM or Engine Control Module will also immediately activate the fuel pump to automatically pump fuel from the tank.

However, in the operation of this injection engine, the fuel pump will turn on for a certain period. This is intended so that the pressure in the injection series or EFI can rise to reach 315 to 340 Kpa. Remarkably, the pump will automatically turn off after a certain time with the help of the ECM.

Usually, the ECU component used in the EFI fuel system is a semiconductor component, such as a condenser. Not only that, if in the conventional system the fuel flows with the help of a fuel pump mechanically, then in the injection system, the fuel will flow by itself. It can even fill up to reach maximum pressure.

When the fuel pressure has reached its limit, the pressure regulator will immediately open the return feed line. This line is useful for returning fuel back to the tank. This process will also run automatically based on commands from the ECU or Electronic Control Unit, which acts like the brain.

Read also: 5 Components of the Fuel System in Cars and Their Functions

2. When the Engine Starts and Runs

The next operation of the Electronic Fuel Injection system is when the engine is in the start and run condition. When the ignition key is turned to the “Start” position, vehicles with the EFI fuel system will automatically rotate the flywheel. This causes the vehicle's engine to rotate or crank. Various sensors related to the EFI system will also work to detect each condition.

The CKP and CMP sensors will inform the ECM that the engine is rotating. CKP and CMP are sensor signals that function to detect engine RPM and the position of cylinder 1's TOP. Thus, the ECM will provide voltage to the fuel pump to keep it running while the engine is rotating or cranking.

Meanwhile, for several other supporting sensors such as MAF, IAT, MAP, TPS, and O2 will serve as references for the ECM in determining the amount of fuel to be injected. To regulate the amount of fuel, the ECM in the EFI fuel system will use injector opening timing settings. 

Nowadays, motor vehicle manufacturers have started producing modes of transportation that apply the EFI or injection system. Even when operated, the vehicle's engine will run smoother because all fuel is regulated logically by the ECM. Not only that, the vehicle's engine will also be more fuel-efficient because the ECM prevents excessive fuel consumption.