digraph G {
size="10,10";  ratio = fill;
node [shape=square,width=1.5];
Voltage_at_plug -> Spark_quality;
Car_cranks -> Car_starts;
Spark_plugs -> Spark_quality;
Spark_quality -> Car_starts;
Distributer -> Voltage_at_plug;
Distributer -> Spark_timing;
Spark_timing -> Car_starts;
Alternator -> Charging_system;
Charging_system -> Battery_voltage;
Battery_voltage -> Voltage_at_plug;
Battery_voltage -> Headlights;
Battery_age -> Battery_voltage;
Main_fuse -> Voltage_at_plug;
Main_fuse -> Starter_system;
Starter_system -> Car_cranks;
Starter_motor -> Starter_system;
}