Only when fuel injectors are functioning correctly can they atomize the fuel properly. When the injector stops functioning you start to experience problems. Fuel economy takes a dive and the engine may exhibit specific symptoms. But you may not be able to tell that the problem is with your injectors.
What are some symptoms of bad or dirty injectors?
Most 460s that are still running will have over 100,000 miles on the odometer. At that mileage, almost all injectors are suspect, and the knowledgeable driver will be anticipating trouble. Non-metalic components of the injector, such as o-rings, for example, will become brittle with age. When they do, the injector can fail. Injectors are all about precision. Their job is to precisely deliver exactly the required fuel for combustion. When injectors become clogged or dirty, they can stick open or closed. When internal components wear out or become damaged from time and the heat from the engine, they can leak either fuel or pressure, or both. Fuel additives build up over time on the injector, forming a crust. Eventually, this crust can cause the injector to fail.
Typical symptoms to look for include a rough idle and/or a hesitation upon acceleration. Also, if you notice the smell of gasoline, you could have injector problems. But be sure to check for leaks elsewhere that could be dangerous, not to mention destroying your fuel economy.
Inconsistent power observed at any speed could indicate fouled injectors, particularly if the engine misfires occasionally. All of these symptoms are caused by an inadequate or inconsistent supply of fuel to the combustion chambers.
How can you tell it is an injector problem?
There are several ways to test your injectors. Some require specialized tools, others do not. One simple way is to pull the injector and visually examine it for obvious signs of problems. First, remove the rail and be careful, as some gas will spill from the removed rail. Remove and examine each injector for any differences. They all should look about the same if they have been in service quite a while.
Another diagnostic procedure is to listen to the injectors with the engine idling. You will need an engine stethoscope to hear it, but placing the tip of the instrument on the injector should reveal a sharp clicking sound if it is functioning properly.
One more tool you could use is a laser thermometer to test the temperature of the exhaust manifold. With the engine warm and running, take a reading on the pipe exiting each cylinder. If the injector is not closing as it should, the temperature will be much hotter than normal. If the injector is failing to open, the temperature will be much cooler. Normal temperatures should range around 450 degrees Fahrenheit. If one or more readings are obviously off the target, that cylinder has a suspect injector. The difference will be clear, as the temperature will be 200 degrees or more off target, either too cool or too hot.
Still another test that is pretty simple requires a means of pressurizing the fuel system. If you have a way to safely do this under controlled conditions of pressure roughly equal to the system’s normal fuel pressure, remove the injectors, attach each one’s inlet valve to a tight-fitting rubber hose, and initiate the pressure through the injector. Then insert the other end in a cup of gasoline and observe any bubbles. If you see bubbles, the injector leaks.
The safest bet if you have an older engine like the 460, is to simply go ahead and replace the injectors. We have you covered if you need injectors, and the good news is that these injectors are nowhere near as expensive as those for newer Ford engines.