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Fuel System Home Page > Parts of the Fuel/Engine Management System > Fuel Injector


Function: Sprays fuel into the engine's intake manifold or cylinders.


Signs of Wear: Sluggish engine performance, poor acceleration, emission noncompliance.















The fuel injector is an electrical valve that controls the flow of fuel into the engine. When voltage is applied to the fuel injector, the valve opens, allowing fuel to pass through the injector and into the intake manifold where it is mixed with the incoming air charge. Fuel exiting the injector is sprayed in a fine mist so that it is mixed completely with the incoming air. The engine computer determines the injector pulse width, or how long the valve on the injector is open. As engine RPM increases, a greater injector pulse width is required.


An internally leaking injector does not create a complete seal at the nozzle of the injector and allows fuel to leak through even when the valve is shut. This can cause poor fuel economy, hard starting, and driveability issues.


When carbon deposits form inside a fuel injector, the flow of fuel can become restricted. Inadequate flow of fuel through the injector will result in a weaker burn in the cylinder and may even cause an engine misfire. Fuel injectors that are restricted will also cause a decrease in fuel economy, as more fuel is added to all injectors to compensate for the injector with the weak flow.


When a fuel system problem is suspected, fuel injectors can be checked by removing them from the vehicle and measuring the amount of fuel delivered by each injector over a specific amount of time. Properly functioning injectors spray equal amounts of fuel, whereas plugged or poorly functioning injectors vary on the amounts sprayed by each injector. This problem is usually resolved using chemical, or ultrasonic cleaners, to remove the carbon deposits.


Have your vehicle fuel and engine management system checked by an ASE Certified Technician in Fuel System Services. Schedule service today to visit our repair facility on the southwest side of Houston.

Fuel Injector - Houston's Premier Auto Repair Facility