Sometimes my car will not start the first time. I press throttle all the way down then turn the key on but no start how to I start an older car with an automatic choke?
An automatic choke is just a bimetallic spring. When the temperature gets cold enough the spring will pull the choke closed.
There are two catches here. The first is that while the spring will put pressure on the choke to close it, it doesn't actually close until pressing the gas pedal at least once. Rapidly pressing and then letting go of the pedal spays in fuel using the accelerator pump and allows the choke to close. The choke won't close on its own because the choke is also tied to the high RPM cam. The cam raises the idle speed while the engine is cold. The cam can only move while the throttle is pressed.
The second is that you can't hold the throttle all the way down because the choke pull off will open the choke. This mode is meant to clear a flood condition.
The standard procedure is to rapidly press the pedal once or twice, let go of the pedal then turn the key to crank.