I have a 1999 Ford Explorer that starts up for about a second and then turns off. The starter is bad but I dont think thats the problem. The gas pump and filter are brand new…so is the battery. Thoughts?
The problem could be with a defective ignition module. Ignition modules function in two modes. These are the START and RUN modes.
During the start mode, the ignition module allows full battery voltage to the coil(s} to provide a hot spark to ensure the cold engine with a rich fuel mixture starts. Once the engine starts and the igntion switch moves to the run position, the ignition module switches to the run mode. The ignition module then steps the voltage down to the coil(s) because not as hot of a spark is required to keep the engine running. This also done so the secondary ignition components last longer.
So it could be that the start mode of the ignition module is functioning, but the run mode of the module has failed.