With the technological advancements of fuel injection systems, many drivability problems disappeared. The fuel injection systems are a big improvement over carburetors. The improvements were seen in the areas of stalling, hesitation, uneven idling, bad fuel economy and difficulty starting. The carburetors were often difficult to start in extreme temperatures and the driver often had to pump the accelerator and then deal with flooded carburetors. The fuel injection system changed all that. Still this is a piece of equipment and it needs to be properly looked after.
The port injection system is the common version on modern cars. This means there is an individual injector at each cylinder. This injector is fixed to sprays fuel into the intake valve. This fuel should be a fine mist that will vaporize immediately. The vapor of air and fuel is what is required for the combustion. The finer the spray then the better the combustion system works.
The biggest issue with fuel injection is dirt. If it is dirty, it can't produce this fine mist. The injectors can stick in a closed position and not spray any fuel, or one can be closed or almost closed with the other works fine. They can also leak out fuel. If the injectors deliver unequal amounts of fuel to the different cylinders it can result in the engine misfiring. As most of the systems today are computerized, what affects one cylinder can affect the other cylinder making the engine run even worse.
The fuel systems are generally very clean. There are filters in the system to trap the bulk of the dirt. Some can get in however. This dirt can cause drivability issues. The other common problem is a gummy residue left after a hot engine is turned off. The fuel at the injector nozzles evaporates and can leave a gummy residue, which can then leave an uneven spray for the next time in use.
Troubleshooting and cleaning
• The simplest and first thing to do is take the vehicle out on the highway and do a couple of full throttle accelerations. That may burn up the gumminess.
• Next is to try a commercial fuel injector cleaner – there are many on the market and most are added to a full tank of gas. Follow the instructors and be sure to add only what is recommended. This same compound can be used on a regular basis to prevent this from happening again as it should keep the injectors clean.
• If this home fix doesn't work, then you will need to take your vehicle in for servicing. Don't mistake cleaning for servicing. Many shops do both, but chances are at this point, you need more than the basics.
o Cleaning involves disconnecting the fuel injector lines from the rest of the system and reattaching to a tank of cleaning solution.
o Next, the injectors have to be removed and cleaned.
o If this still doesn't do the job then the fuel injectors may need to be replaced.
• When you are getting the fuel injector system serviced, make sure the following steps are covered:
o Check fuel pump for correct operating pressure and volume.
o Test the pressure regulator to make sure it is operating and not leaking.
o Flush entire fuel rail and upper fuel injector screens to include pressure regulator.
o Clean fuel injectors. o Decarbon the whole engine assembly.
o Clean the throttle plate and idle air control (IAC) passages.
o Check the minimum airflow rate and adjust if needed.
o Check and relearn onboard computer.
If you consistently use cheap gas and don't follow the recommended maintenance schedule, you will see an increase the accumulation of carbon deposits. This of course, leads to decreased horsepower and poor fuel efficiency. Both of which can be helped by proper fuel injector maintenance.