Fuel Injectors – Usually Only Fail, In One Of Three Different Ways

Fuel Injectors - Usually Only Fail, In One Of Three Different Ways
Fuel Injectors - Usually Only Fail, In One Of Three Different Ways

So, today’s fuel injectors are a vital part, of a complex fuel management system.

Fuel injectors, are basically a spray nozzle, that atomizes the fuel. Then, performs the final stage of delivery, to the engine.

So, if the fuel injectors are not operating properly, then other parts of the engine, will be affected as well. In addition, if its job is thrown off, by restrictions electrical problems or fuel problems, then it can cause driveability issues.

Furthermore, new technology has made fuel injectors more precise than ever, in dispensing fuel.

Consequently, vehicles regulate your speed and acceleration, by varying the ratio, of the fuel and air, entering the engine.

New Fuel Injectors
New Fuel Injectors

In order to provide the right amount of fuel, the (ECU) is equipped with, a whole lot of sensors.

Fuel injectors deliver fuel to the combustion chamber, directly or indirectly. During its evolution the fuel injector has moved, from the intake manifold, to the combustion chamber.

Common Types Of Injectors Include:

  • Throttle Body Injection.
  • Multiport Injection.
  • Sequential Injection.
  • Direct Injection.

A Fuel Injector Will Usually Only Fail, In One Of Three Ways:

1. From Being Dirty Or Clogged

Consequently, over time the nozzle of the injector can become, dirty or clogged. So, when you shut off your engine, the injector will soak up heat from the engine.

Dirty Or Clogged
Dirty Or Clogged Fuel Injectors

This causes any fuel left in the injector to evaporate, leaving behind hard deposits, inside the injector. Over time, these will eventually, block the injector.

2. Leaking Externally Or Internally

So, the most common cause of leaking injectors, is the failure of the O-ring. And, is usually where the injector, meets the fuel rail. The O-ring can become, hard and brittle, from the heat of the engine.

Damaged O-Ring
Damaged O-Ring Causing Injector Leak

If it breaks, then fuel can leak out, over the engine. The other way an injector will leak, is if the injector body or nozzle cracks.

3. From A Mechanical Failure

There are many moving parts, inside an injector and over time, they can fail. As a result, of normal wear and tear or lack of maintenance.

Possible Signs Of Fuel Injector Issues, Include:

  • Hard Starting, when engine is hot
  • Poor idle
  • Failed, emissions test
  • Poor Performance
  • Engine does not reach full (RPM)
  • Increased fuel consumption
  • Rough, engine performance
  • Surging and bucking, under various throttle loads
  • Smoke from the exhaust
  • Oil thinning, which can lead to, complete engine failure
  • Engine Knock or Detonation, which can lead to, complete engine failure
  • Pollution

Tracking Down The Problem

Hook Up An (OBD-II) Code Reader

So, when looking for problems, always start by hooking up an (OBD-II) code reader. This will tell you, if the (ECU) has logged any errors. If an engine misfires because of a bad injector, there will be an error code. And, that code, will point to the injector in question.

(OBD-II) Code Reader
(OBD-II) Code Reader

If you are using a “generic” code reader, then you can expect to see codes, beginning with P02. (generic, not vehicle manufacturer specific). For example, a fault with an injector in cylinder one, would give a code of P0201. These are all, fuel & air metering injector circuit related codes.

Listen To The Fuel Injectors

Another helpful diagnostic tool, is an mechanic’s stethoscope. This tool enables a vehicle owner, to listen for any problems with the fuel injectors. And, is done by placing the tip of the stethoscope, on each injector.

Mechanic’s Stethoscope
Mechanic’s Stethoscope

Fuel injectors, make a sharp clicking sound, when they are working properly. So, the absence of this sound, can indicate a problem, with an injector.

How To Prevent Fuel Injector Problems

In general, fuel injectors are hard wearing and with a little care, can often last, the life of the engine. Like any other engine part, regular maintenance is the key, to keeping them going. So, if you plan on running up high mileage, then there are a few things you can do to help.

Regular Inspection And Cleaning

So, there is a way to keep your injectors, in good working order. And, that is to have them, removed and inspected at regular intervals. Under normal circumstances, that would be, every 25,000 miles or 40,000 km. However, if you tend to do a lot of short trips. Then, you’d probably want to have them looked at more often, to prevent the build up of deposits.

Use Of Fuel Additives

Another great way to keep injectors in good health, is to regularly add, a fuel injector cleaner. You just add it, to your fuel tank. Many manufacturers claim that these Additives, will give your engine, extra power or added mpg.

Fuel Additives
Fuel Additives

They probably won’t, or make much difference, to a engine that is running properly. I usually do not recommend Additives, but this is one area, that does help.

Regular Engine Servicing

Regular oil and filter changes, will go a long way, towards maintaining a healthy engine. If an engine isn’t running efficiently, this can load extra pressure on injectors. It’s also important, to regularly change the fuel filter, to ensure a proper fuel flow.

Driving Habits

Driving a vehicle hard, along with short start stop trips, will increase the wear and tear on injectors. Letting the engine cool down, before turning it off, will increase the life of the injectors. As a result, a well kept fuel injection system, will keep your vehicle going for years.

Sometimes A Faulty Fuel Injector, Can Be Repaired:

Leaking Injector

If the O-ring fitted to the injector is the problem, then replacing this O-ring, will usually fix the leak. If the injector body, nozzle or internal parts are cracked, then a new or refurbished injector, is your only option.

Damaged Injector O-Ring
Damaged Injector O-Ring

Replacement fuel injector seals and washers are cheap and are, fairly easy to install. This can often fix the problem, and if you are handy with a wrench, it’s not that difficult to do.

Dirty Injector

It is fairly inexpensive, to have your fuel injectors cleaned and overhauled, by a professional. This involves inspection and cleaning of the injector. That’s why, it is recommended, that you should get them cleaned, at regular intervals. Also, to help prevent problems, down the road.

Fuel Injector Additives
Fuel Injector Additives

It can also be a good idea to run, a fuel system cleaner through your engine. Usually, a couple of times a year. This will help to keep injectors, fuel pumps and fuel lines, clean and clear, of carbon build up. It will also, increase the service intervals of the injectors.

Clogged Injector

Clogged injectors, can usually be repaired, if you catch the problem quickly. Sometimes a fuel injector, is completely clogged, because of years of neglect or a lack of, regular engine servicing. If this is the case, then a refurbished replacement, may be the only option. Again, regular use of a fuel system cleaner, can help to prevent, clogged injectors.


So, fuel injectors, do not last forever. But, you can take steps, in making them last, as long as possible. Also, fuel injectors are, a very important part of modern vehicles. Not only do they deliver fuel to your engine. But, they do so in a manner that is, efficient as possible.

This not only gives vehicles, better fuel mileage. But, it also cuts down on the pollution, that they emit, in comparison to older technologies. When something goes wrong, with this sophisticated technology, it can feel intimidating for many vehicle owners. As a result, leading them to often take their vehicles, for a professional diagnosis.

Thank You !