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.