Reasons Engine Cranks Over but Won't Start - Toyota Service Information To Know in Salem, OR

If your car won't start, and you're not exactly handy under the hood, it can be a stressful situation indeed. Not only are you stuck without the transportation you need, you may be in need of a costly repair to get you back on the road. We want you to be confident when you need maintenance and repairs on your car, so here are four important things to know if your car cranks but doesn't start when you turn the key.

If turning the key (or pressing the engine start button) causes the starter to turn the engine, but the engine doesn't begin running under its own power, that tells us a few things. For one, it tells us that your starter motor is working. It also tells us your car battery has a charge. Since we can eliminate those as potential causes, our technicians will move on to checking for the following four things when your car won't start.

Testing Fuel Injectors

4. Insufficient Fuel Pressure

It's the detonation of fuel inside the engine's cylinders that force the pistons down, turning the crankshaft and ultimately moving your car. Naturally, if no fuel can get to the engine, combustion can't begin and the engine won't start.

This particular problem has a variety of potential causes. Most commonly, its caused by a fuel pump that's not working. The fuel pump fuse may have blown, or the fuel pump itself will need to be replaced. Alternatively, this problem could be caused by a leak in the fuel lines, clogged fuel injectors or a bad fuel pressure regulator.

Two Spark Plugs

3. Blocked Airflow

If fuel is getting to the engine, the next thing to look for is air. If not enough fresh air can get to the engine, it may run roughly or not run at all. This could be caused by something as simple as a clogged engine air filter, but it's more likely to be the result of a faulty sensor.

O2 sensors and the Mass Airflow Sensor detect the amount of air present in the engine. This information allows the computer to adjust the air/fuel ratio for maximum efficiency as you drive. However, these sensors can become fouled with carbon over time. Fouled O2 sensors can't send the necessary data to the engine control module. They'll need to be cleaned or replaced if they stop working, which can lead to problems like engine stalling and hesitating while the vehicle is running, as well as difficulty starting the vehicle at all.

2. Lack Of Spark

Once the air and fuel have mixed inside the engine, all it takes is a little compression and a spark to detonate the mixture and start the engine turning on its own power. That's why each cylinder has a spark plug. The spark plug lights at the precise moment in the engine's cycle to combust the mixture. But if the spark plugs aren't working, or fire at the incorrect time, the engine may not run.

One reason the spark plugs may not work is a dead battery -- but since the engine cranks when you turn the key, we know the battery has some juice in it. More likely, this problem is caused by a timing issue. The engine could've come slightly out of time, or the crankshaft position sensor has malfunctioned. Without accurate information about where in its travel the crankshaft is, the spark plugs wont spark at the right time, causing your engine to stall or fail to start in the first place.

Starter Motor Cutaway

1. Broken Connection To Starter Motor

So, the engine has fuel, air, spark and there's electricity in the battery to run the starter motor. Why won't the car start? At this point, we may want to take a close look at the physical condition of the starter and its connection to the engine.

An engine can't start under its own power. It just needs an initial turn to begin the combustion cycle. The starter is a small but mighty motor that uses a small starter gear to engage the engine's large, heavy flywheel. That's why starting a car takes quite a bit of power from the battery. When you turn the key, the starter gear meshes with the flywheel and gives it a turn. If the starter cranks, and the engine is in good shape, but it simply won't start, the teeth of the starter might not be meshing properly with the flywheel. While it's unlikely, our technicians can diagnose this problem and replace the broken components.