Eli5: Why does pressing the accelerator helps when the car engine is not turning on?
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This is especially true of older cars with a carburetor.
A car engine requires a specific mixture of fuel and air to start and run efficiently.
When a car engine is warm, the air that it pulls in to mix with the fuel tends to also be warm. Warm air is less dense than cold air. This means that when the engine is warm it needs less fuel mixed with the air than when the engine is cold. This air fuel mixture is what is detonated inside the engine eventually to make power.
Stepping on the gas pedal on one of these older cars connects to a mechanical linkage in the carburetor that squirts more fuel into the engine which can help with that air fuel ratio when the engine is cold.
You have to be careful though, because you can squirt too much fuel into the engine, which is sometimes called “flooding it”
Stepping on the gas pedal while starting the car probably doesn’t make a difference in a fuel injected car (one made after the 80s.) Fuel injected cars have a computer that controls the air fuel ratio during start up. The computer is paying attention to things like air pressure, air temperature, and engine temperature and automatically squirts the appropriate amount of fuel into the engine.
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