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Diagnosis and Rectifying Electric Fuel Injector System

A simple Electric Fuel Injection is a system containing an Electronic Control Unit, a fuel pump, fuel injectors and a couple of sensors. To construct a working electric fuel injector system, we need to have; a fuel injector pump to pressurise the fuel to a higher needed pressure; high-pressure pipes are the horse that will transfer the pressurised fuel to the injector nozzle. Injector nozzle will inject the fuel into the combustion chamber, the feed pump will suck the fuel from the fuel tank, fuel filter is a sieve that will filter the fuel, returning spring will provide the mechanism of opening and closing of fuel passageway. Electronic Control Unit will computerise the whole system from the flow regulation of pressure and opening and closing of the return spring (Jacob and Ashok, 2020).

The Electric Control Unit collects data on engine conditions and specifications such as air pressure, air intake temperature, accelerator position, engine temperature and engine speed. These things happen in milliseconds. These sensors send data to the Electric Control Unit, which uses it to calculate the correct amount of gasoline to inject into the cylinders. The Electric Control Unit instructs the injector valve when to open to allow fuel into the inlet port. After determining the engine’s condition, fuel is sucked from the tank, conduits through the fuel lines, and pressurised by fuel pumps. A sensor checks and regulates the fuel pressure, and then fuel is separated using a fuel rail to supply the injector. Finally, the injectors are signalled to inject the required amount of fuel. The exact gasoline/air combination necessary depends on the engine, fuel, and current demands, such as power, fuel economy, exhaust emission levels.

Since it’s an electronic component, the system is damaged mainly by foreign objects. For instance, the fuel injector typically gets contaminants such as carbon that builds up within the injector, causing it to be clogged either partially or entirely, hence preventing the injector from closing all the way. This clogging causes a drip in fuel injection, creating; a misfire, struggling to start, fuel smell in the car, lack of power and rough idling.

According to Petruzzelli (2013), when diagnosing a fault in a fuel injector, first look if the vacuum hose is removed detached from the fuel-pressure regulator when the engine is running. Check the following if the fuel pressure does not increase, then the fuel pump does not supply enough pressure. If there are engine oil fumes inside the air cleaner assembly, the technician should check a clogged PCV system by visual inspection on the Throttle Body Fuel Injection system. To identify a fault in the wiring system or the sensors, the technician should hear if the fuel injectors are making the same sound using a stethoscope. Also, fuel should be hard flowing back to the fuel tank due to the difference in pressure between the fuels pump and fuel regulator.

Finally, to check if there is leakage in the injectors, the technician should deactivate the ignition system, unlock all injectors and check the possibilities of hydrocarbons in the exhaust system. Most electric fuel injectors use a pickup coil or crank sensor pulse to trigger the injector to spray the fuel. When there is no signal received, there will be no fuel injected; hence the technician will start by inspecting the ignition system for a fault and then test the entire fuel system components.

Where the technician is doing a diagnosis test, there are some equipment used to help acquire accurate readings from the three major points, including electronic signal failure, fuel pressure problems, and the volume of fuel problems. First, we use a Fuel Pump Relay Circuit Diagnosis using a digital multimeter, and the coil will be at terminal 30 and contact 87a for open and 87 for the closing of the relay. And the reading in the relay should be around 4.8 amperes since the range is between 4 to 8 amperes, and the coil’s resistance should be between 60 to 100 ohms. To check the correct fuel pressure measurements, a graphing multimeter or a digital storage oscilloscope is used. This allows the technician to check the fuel pressure drops from a 15 PSI mark to 6 PSI in 60 seconds, and then the system is faulty the manufacturing mark is about 10% after 10 minutes when idling. When checking the fuel pump volume, a calibrated pressure gauge is inserted into the container, and the readings are checked; they should range from 0 when empty to 1023 mark when full (Petruzzelli, 2013).

After the technician has diagnosed the problem, there is a correction. The first step is always cleaning the affected part by using cleaners specified to the type of vehicle, then placing the cleaning kit in the fuel port. Then disable the engine fuel pump and insert a loop for the fuel to flow back to the fuel tank, disengage your fuel pressure regulator, connect a compressed air hose to the cleaning kit and change the pressure levels. Now start the engine, let the cleaning kit absorb the cleaning solution, and let the engine run until it automatically shuts. After cleaning, put back the new or maintained fuel injector, which must be carburised steel, using a fuel installer kit. Also, after every insertion of the fuel injector, you should use a stethoscope to hear the clicking sound if the injector valve is open, and then use a pressure test to check if the pressure of the fuel is correct.

Labelled Diagram for Electric Fuel System

Figure 1 showing diagram for electric fuel system

Diagram for electric fuel system


Jacob, A., & Ashok, B. (2020). An interdisciplinary review on calibration strategies of engine management system for diverse alternative fuels in IC engine applications. Fuel278, 118236.

Petruzzelli, A.M., 2013. “A Story of Breakthrough: The Case of Common Rail Development”, 35th DRUID Celebration Conference 2013, Barcelona, Spain, June 17-19, doi:10.1142/S1363919615500346


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