Problem is I try to start my Mustang and the car will start , but once you disengage the starter it dies . It fires up for a second , but as soon as you let off the starter and put the key in the on/run position it just dies . Any ideas ?
You may have a bad ignition switch or relay. The ignition switch is the part that connects the battery to the starter and the ignition system. The relay is the part that controls the power to the ignition switch. If either of these parts is faulty, they may not be able to maintain the power to the engine after you release the starter. You can test the ignition switch and relay with a multimeter or a test light to see if they are getting and sending the proper voltage
• You may have a bad fuel pump or fuel pump relay. The fuel pump is the part that delivers fuel from the tank to the engine. The fuel pump relay is the part that controls the power to the fuel pump. If either of these parts is faulty, they may not be able to provide enough fuel pressure to keep the engine running. You can test the fuel pump and fuel pump relay with a fuel pressure gauge or a test light to see if they are getting and sending the proper voltage
• You may have a bad mass airflow sensor or throttle position sensor. The mass airflow sensor is the part that measures the amount of air entering the engine. The throttle position sensor is the part that measures the position of the throttle. If either of these parts is faulty, they may not be able to send the correct signals to the computer, which may affect the air-fuel mixture and cause the engine to stall. You can test the mass airflow sensor and throttle position sensor with a scan tool or a multimeter to see if they are sending the proper voltage.
These are some of the most common reasons why a car starts and then dies immediately. However, there may be other causes as well, such as a bad crankshaft position sensor, a bad camshaft position sensor, a bad idle air control valve, a bad spark plug, a bad coil pack, or a bad injector. To diagnose these problems, you may need more advanced tools and skills, or you may need to take your car to a professional mechanic.