Reasons the Engine Turns Over but Your Car Won't Start - Service Questions at Capitol Chevrolet

Imagine this: you turn the ignition key or press the start button in your car, you hear the familiar cranking, and then . . . that's it. The cranking continues, but the usual sound of the engine roaring to life doesn't happen. If this happens to you, chances are it's not the starter. Instead, it's likely because your engine isn't getting at least one of the four major components it needs to start: fuel, air, spark, or compression. On this page, we'll take a look at all four of these things, as well as these things could cause the engine not to start.

If your engine isn't getting enough air, starting it may be difficult or impossible 

4. Air

For combustion to take place, there needs to be a precise mixture of fuel and air. While it's not incredibly common, a lack of air may be causing the engine not to start. This could be due to an overly clogged engine air filter, which can often be fixed simply by replacing it. There are some other possibilities, as well, including a vacuum leak.

3. Fuel

Much more likely than the engine not getting enough air is the engine not getting enough fuel. This may mean that there's not any fuel in the tank, in which case filling it up again may do the trick. However, if the lack of fuel is due to a leaky or damaged gas tank, you should instead have the vehicle towed. But an empty tank isn't the only reason an engine might not be getting the fuel it needs. The fuel filter may be clogged, or the fuel pump might have sustained some damage. In these cases, the fuel wouldn't be able to get from the tank to the combustion chambers. Or, you may have clogged fuel injectors.

 
If your fuel tank is empty, your car may not be able to start 

2. Spark

If your car has a gas engine, a spark is what causes the fuel and air mixture to combust. This spark is, fittingly, provided by spark plugs. When a spark plug fires, a small spark is created in the gap between the electrodes. Each spark plug fires at least hundreds of times a minute, so a plug that isn't working is a big problem. If your engine isn't getting the spark it needs, it could be that one or more spark plugs need to be changed. As time goes by, the space between the electrodes may become imprecise, making it necessary for the plug to be replaced. However, there are problems other than the spark plugs themselves that could cause them not to fire, so components like the distributor may be to blame.

Spark plugs are vital to your engine's functioning, so a bad plug may cause an engine not to start 

1. Compression

Even though gas engines don't use compression to actually ignite the fuel like diesel engines do, compression is still a vital part of the process. If one of the cylinders in the engine has low compression, the engine may not be able to start up. This could be caused by a loose timing chain, bad head gasket, stuck valve, or bad piston rings. Whatever the cause, it's best to have it looked at by an expert.