* No air-fuel mixture: An internal combustion engine needs a precisely metered mixture of air and fuel to ignite and run. The throttle body controls the airflow into the engine. Pouring gas directly in bypasses the entire fuel injection system and the critical air metering components. The resulting mixture will be far too rich (too much fuel, not enough air), leading to an inability to ignite properly.
* Engine flooding: The excess fuel will flood the engine, preventing proper combustion and potentially damaging sensitive engine components.
* Potential for fire: Gasoline is highly flammable. Spilling it near hot engine components increases the risk of a fire.
* Sensor damage: The fuel and excess liquid might damage sensitive sensors in the intake manifold, leading to further engine problems.
In short, while you might get a brief sputter or backfire, pouring gas into the throttle body is a highly ineffective and potentially dangerous way to try and start a vehicle. If your truck won't start, diagnose the problem properly (check the fuel pump, battery, starter, etc.) or call a mechanic.
