Ford Fuel Injector Failure: What Causes It And How To Fix It

Once automotive manufacturers decided to build their engines with fuel injection, they saw an increase in fuel efficiency and fewer pollution-causing emissions. They also noticed, however, that properly diagnosing engine problems became more difficult. Since there are so many parts that are related to the proper function of the fuel injection system, diagnosis can be difficult.

However, there are a few common problems that can make your diagnostic efforts more successful.

The Basics Of Fuel Injection

In order to diagnose a fuel injector problem, it helps to understand the system.

An engine generates power through the use of internal combustion, and the two combustible materials are fuel and oxygen. The engine draws in oxygen by way of the air intake and fuel from fuel injection. There must be a balanced mix of air to fuel in order to get an efficient mix. This is regulated through sensors, your Ford’s engine computer, and the injectors.

The fuel injectors are electronically controlled by the car’s engine control unit. Fuel is pumped into the injectors, and then they are told to open and send the fuel into the engine through jets by way of a fine mist into either the intake manifold or the cylinder (or both). The more fuel that the engine is demanding, the longer the valves controlling the mist stay open, which is defined as "pulse width."

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Common Problems And Symptoms

By addressing the most common issues and their symptoms, you will be better able to make a diagnosis of a fuel injection problem.


  • Dirty Fuel Injectors - Residual fuel additive that is not dispensed within the manifold can leave a film on the fuel injectors. It can become a crusty coating on the injectors because of the heat within the engine. This residue can clog the injectors, impeding the spray.
  • Clogged Fuel Injectors – Many things can clog up the fuel injectors. Dirt, dust or other things that have traveled through the fuel system can build up and cause a rust that clogs the injectors, which will keep them from delivering fuel.
  • Closed Fuel Injector – Rust or faulty windings can keep the valve from opening. A winding can short out, overheat or break. Rust can cause it to stick. If it can't open, it can't deliver fuel.
  • Open Fuel Injector – A faulty spring or rust build-up can cause a valve to stick in the open position. This will cause the injector to leak fuel.
  • Leaky Fuel Injector – If a fuel injector overheats and fails, it will cause a leak. Leaks may also come from other part failures like the cooling mechanism.


  • Engine Power Inconsistency – An engine that revs high or low and an RPM gauge that fluctuates can be a result of a dirty fuel injector.
  • Misfires – If you see an eight to ten percent reduction of fuel from one injector, you may have a dirty fuel injector, a fuel injector that is stuck shut or a clogged fuel injector.
  • Uneven Idling – If your engine is not idling smoothly, there can be an uneven distribution of fuel to the engine. This is usually caused by a dirty fuel injector.
  • Fuel Smell – A faulty injector will cause a fuel smell since it is leaking. This can be due to the fuel injector not closing or leaking.
  • Poor Fuel Mileage – A drop in fuel mileage can indicate that an improper amount of fuel is being delivered to the engine. It may be the result of a fuel injector leak or an injector that is not closing.

By recognizing the problem and symptoms, you are better prepared to diagnose your injector problem.

Diagnostic Testing

Ford fuel injectors

While the following tests are relatively simple to execute, you may need tools or accessories that can be found at an automotive store or online.

  • Exhaust Manifold Temperatures – If you have an open fuel injector, the fuel is not controlled, so it continues to spill out where it overheats. The exhaust manifold will be at higher than normal temperature. Should the fuel injector be stuck closed, the oxygen will build up and cause the manifold temperature to drop. While the engine is warm, use a laser thermometer and point it at the exhaust manifold pipes. Each cylinder should read plus or minus 30 of 450F degrees. An injector that is stuck closed will give you a reading of 200 to 250F, and one that is stuck open will cause the temperature to rise up to 600F or more.
  • Fuel Injector Sound – By using an engine stethoscope, you can listen to your car’s engine. Place the tip onto the injector, and if you hear a sharp clicking sound, they are operating properly. If they are silent, they are not working.
  • Fuel Injector Inspection – You can take the injectors out of your Ford and inspect them for damage, dirt, or rust. You can start by removing the fuel rails and detaching each injector from the rail. When you remove the injector, there will be fuel that spills out of the rail, so make sure you do not get it on yourself or the ground.

Without a properly operating fuel injector system, you will not get the right amount of fuel to your engine, so if you start to see any of these signs, you need to take measures to correct the problem as soon as you can. Not only will your fuel efficiency increase, but you will be expelling fewer emissions also. If you run into any problems, contact your local Ford dealership for assistance.

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