Useful Tips to Diagnose Fuel Injector Problems

The creation of fuel injectors has represented a major development in automotive engineering, as these parts have been able to provide the benefits of making cars both more fuel-efficient and less polluting. Fuel injectors play a very important role in the functioning of a vehicle because they deliver gasoline to the car's engine. This important role, coupled with the moving parts of this engineered component, makes the idea of identifying problems with a fuel injector somewhat daunting for many drivers. Most car owners may not realize that they can identify these problems on their own though, which can save them large sums of money by not needing to bring their cars to service shops.

This guide provides car owners with instruction about how to diagnose fuel injector problems, first by explaining fuel injection systems and the role that fuel injectors play in them, then by identifying both common fuel injector problems and symptoms of these problems, and finally, by detailing instructions on how to run a few basic diagnostic tests. After readers finish reading this guide, they will feel confident that they can successfully diagnose fuel injector problems without bringing their vehicle to professional mechanics.

Understand Fuel Injectors

Before setting to work diagnosing fuel injector problems, it helps to understand what fuel injectors are. This section describes the basic process of how a fuel injection system works and the role that fuel injectors play in this process.

Fuel Injection System Basics

A car's engine uses an internal combustion process to generate power, with the two key ingredients to this process being oxygen and fuel. The engine takes oxygen from the air surrounding it and fuel from the reservoir that holds the car's gasoline. An air intake system delivers the air to the engine and a fuel injection system delivers the gasoline. The engine's gas supply is limited, so in order to use it efficiently the engine must apply the right amount of gasoline to mix with the oxygen that it is receiving. Since the oxygen supply fluctuates, the fuel injection system must constantly change the amount of gasoline that it delivers, and it must deliver the gasoline in a precise manner so as not to waste any of it.

The Role of Fuel Injectors

Fuel injectors play a very important role in the engine's fuel delivery system in that they deliver the exact amount of gasoline that the engine needs, even as the requirements shift quickly and constantly. An injector is a valve with electronic controls that receives signals from the engine control unit. A gas pump delivers pressurized gasoline into the fuel injectors and the engine control unit tells the fuel injectors to open a valve to let the pressurized gas pass through an atomizing nozzle. The fuel injectors thereby spray a fine gasoline mist into the engine's intake manifold, which then delivers it to the engine for combustion with the oxygen that the engine is receiving. This mist makes for more efficient burning of the gas in combustion than if it were in droplet form. The more gasoline that the engine requests, the longer the valves in the fuel injectors stay open. Pulse width describes the amount of time that the valves stay open.

Becoming Familiar with Common Fuel Injector Problems and Their Symptoms

This section describes the problems and symptoms that are related to fuel injector problems. It is important for readers to be familiar with these problems and symptoms if they plan to diagnose the fuel injectors on their own, as this will help them to accurately diagnose problems.

Common Problems

This section lists the most common problems that are associated with fuel injectors. Some problems are easy to correct, while others require replacement of the fuel injectors.

Dirty Fuel Injectors

Fuel additives that do not spray into the intake manifold can leave a residue on the fuel injectors. These can burn and form a crust because fuel injectors run very hot due to the friction that is produced from rapid and repetitive movement. The crust on the fuel injectors can result in a weak spray and an uneven pattern.

Clogged Fuel Injectors

Fuel injectors can also clog from the buildup of microscopic foreign objects, which are usually in the form of rust. This is typically introduced from a source upstream in the gasoline supply, such as the fuel supply line or the fuel rail, and it can result from a car sitting idle without maintenance for a long time. A clogged fuel injector will not be able to supply gasoline to the intake manifold.

Fuel Injector Does Not Open

The valve in the fuel injector might not open as the result of faulty windings or as the result of a rusted fuel injector. The windings might overheat, short out, or break, and rust can cause the valve to stick. In any of these instances, the valve will not open and the fuel injector will be unable to deliver gasoline through its nozzle.

Fuel Injector Does Not Close

The valve in the fuel injector might also be unable to close due to a faulty spring or due to a buildup of rust or fuel additives. If the valve is unable to close properly, the fuel injector will leak gasoline.

Fuel Injector Leaks

The fuel injector may also leak gasoline if other parts of the system fail, such as the mechanism that cools the injector. The fuel injector can then overheat and fail, resulting in a leak. It is also possible that the injector has a faulty part that does not enable it to function properly.