Fuel, air, and electricity are the three essential elements to start and run a gasoline engine. When anyone of them is missing or insufficient your engine won't start and run. This knowledge gives you enough confidence to diagnose a no-start problem of your car. After turning on the ignition a few times the condition of the spark plug can give you the tell-tale signs of your failure to start the engine. Disconnect the HV cables one at a time and mark which spark plug they came from. Remove the spark plugs and look at the condition of the electrodes at the spark gap ends; if the electrodes show traces of unburned fuel it could just be a failure in the ignition circuit. There must be fuel, air, but no or insufficient electricity is reaching the spark plug gap. If there are no traces of fuel in any of the spark plug; the fuel line, fuel pump, fuel filter and including the air filter system must be checked.

The diagnosis would have been simpler if the failure to start is caused by a jamb starting gear assembly or burned starter motor or failure of the starting solenoid or weak battery. The engine won't turn at all with a jamb gear assembly; a burning smell could be traced to the starter motor; and if a click is all you hear and the solenoid is cold after a few flips of the ignition switch there must be no electricity flowing to the solenoid coil. When you turn the ignition switch and the starter does not develop enough torque to turn the engine, you have a weak battery.

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