An engine that refuses to start is frustrating. Besides leaving you stranded without transportation, the problem’s root cause is usually a mystery. Finding and fixing the issue takes a bit of investigative work.

If you’re familiar with your ignition system, and understand how it works, troubleshooting a no-start situation is much easier. It’s a matter of going through each of the relevant parts methodically, and testing them. The current starts with your battery. It flows to the ignition switch, and onward to your brake pedal, starter solenoid, and starter motor, which fires your engine. Problems can develop anywhere along that path.

The goal of this article is to give you a blueprint for diagnosing a non-starting engine. There are two scenaros; each is defined by whether the assembly cranks (i.e. turns over). We’ll cover both scenaros, and describe the most common problems that occur.

Scenario #1: Engine Refuses To Crank

You climb into your vehicle, turn the key, and nothing happens. The engine refuses to crank. There are a lot of elements that might cause this situation, such as a bad battery, failed starter, or malfunctioning ignition switch.

With a bad battery, you’ll need to check the voltage output. Just because the battery is dead does not mean it’s useless. It may have simply drained due to leaving your headlights on overnight, a corroded connection, or a problem related to your car’s charging system.

If you suspect your starter relay may be the culprit, check its connections and voltage. You should be able to run the battery straight to the starter to test whether it moves. If the battery and starter relay are fine, check to make sure voltage is passing through your ignition switch. If it’s not, you’ll need to replace it.

Scenario #2: Engine Cranks, But Refuses To Fire

In this scenario, you can hear your engine turning over, but it refuses to start. The fact that the assembly is cranking means your ignition system is working properly. This means you can rule out the individual pieces of that system. In most cases, a cranking engine that doesn’t fire is caused by insufficient fuel, spark, or compression. All three are necessary.

Possible Reasons For Insufficient Fuel

One of the most common reasons the engine receives too little fuel is due to a bad fuel pump. When the pump is working, it makes a noticeable noise when you engage the ignition. Have a friend turn the key so you can listen for that noise (you’ll need to lift the hood). If you are unable to hear it, the pump is likely failing, and needs to be replaced.

Occasionally, the component that manages pressure to your fuel injection system may fail. If it does, your engine won’t receive enough fuel, and consequently, will fail to start.

Lastly, check your gas gauge to make sure you have sufficient gasoline in your vehicle.

Possible Reasons For Lack Of Spark

A spark is necessary to ignite the air-fuel mixture inside your engine’s cylinders. While the spark plug is the part that ultimately delivers the spark, there are other components that must work properly in order for the plug to do its job. The spark plug wires, distributor, ignition coil, crank position sensor, and PCM must function for the necessary voltage to reach the plugs. Thus, each of these parts needs to be tested to either rule them out, or identify them as the cause of the no-start.

Possible Reasons For Insufficient Compression

Prior to being ignited, the air-fuel mixture is compressed within each of the cylinders. If there is a compression leak, your engine’s operation will suffer. Most leaks can be traced to the valves. If the intake or exhaust valves fail to close properly, the air-fuel mixture will not be sufficiently compressed. Combustion will be less efficient, and less clean. If there is a severe lack of compression, your engine may refuse to fire.

If you have experience working on your car, and own a few diagnostic tools, you should be able to pinpoint the cause of a non-starting engine. Otherwise, have a trained mechanic identify the culprit.

Author Bio: Visit Everdrive.com for all your used engines needs. Check out the leader in parts, Everdrive.com

Category: Automotive
Keywords: car won\’t start, why the car will not start, used engines, why the car won\’t start,