Q: Car turns over but won't start

Hello. A crank, no start can be caused by a number of problems. The most common being a fuel system problem. If there is not a buzzing noise coming from the fuel pump when the key is first turned on then the pump may be bad. If the pump is working then it may be a bad crank sensor or a bad ignition module. All of these are common failures, but there are also less common problems such as a bad ignition switch. A mechanic would start diagnosing this by checking the fuel pressure to see if it is above manufacturer specifications. If it is not then the pump is usually the first to be replaced. If the pressure is fine the spark is checked. At that point a scan tool will also be used to see if there are any codes and to see if there is a crank signal.