Bad Fuel Injector Symptoms

Fuel injectors have revolutionized the way cars burn fuel. That being said, they can fail just like any other part. In this article, we look at bad fuel injector symptoms.

Every new car since 1990 has been built with a fuel injection system of one type or another. The most common types are multiport and sequential injection systems. Regardless of the type, the systems all have similar components. Most people focus on the fuel injectors when there seems to be a problem, but the issues can range from bad sensors to solenoid issues and, well, a host of things. Still, injectors can definitely go bad so let’s take a look at some common symptoms.


A lack of power is a classic bad fuel injector symptom. The injectors are probably not bad, but just plugged to some extent. This leads to the engine running very lean because the fuel is not getting into the system. The computer [“ECU”] that controls the injection might not read the lack of fuel getting into the engine, which means no correction will be made to the fuel input. This will result in a lack of fuel in the ignition chamber and a lack of pressure to push the piston down and turn the crankshaft.

Stalling and misfiring are also classic signs of bad fuel injectors. The fuel injection system is like a precision drum performance. When the drummers are all synchronized, the sound is amazing. If they get out of synchronization, it just causes headaches. The same is true for your engine. A lack of fuel will choke off an engine just as a lack of food is going to cause you and me problems.

Your car will not start. Is this a bad fuel injector symptom? It can be, but it is unlikely. You would have noticed all kinds of symptoms before this step including stalling, inability to idle and so on. The chances of all your injectors going bad at once are remote, but some cars may shut down if one or more plug completely to keep your engine from being damaged. Regardless, you need to get to a mechanic asap!

It should be noted that the fuel injection system is…a system. While fuel injectors go bad, problems with any part of the system may produce the same bad symptoms mentioned above. The primary culprit is often a bad sensor. The ECU relies on sensors to determine how much fuel should be put through the injectors. If the sensors aren’t working, the ECU is going to make incorrect decisions and the car is going to run poorly. Put another way, don’t just look at the injectors.

The fuel injector is a brilliant little device, but the key word is “little”. The fuel passes through an astonishingly small path through the injector. It must pass through a small filter in the injector, around a plunger and out the spray tip end. Even the smallest of debris can plug the average fuel injector. This is why you should never drive until your gas tank is nearly empty. The debris on the bottom of your gas tank will plug up your injectors.

There are plenty of bad fuel injector symptoms. The bigger issue is fixing the injectors. You can try to clean them with additives, but bigger problems usually require a mechanic because fuel injection systems have become so advanced.

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