First, if you are talking gasoline vapor (gas), then you will not easily 'vaporize' it without unintended ignition due to the low flash point of refined gasoline. Then, the next problem would be transporting that gasoline vapor into the combustion chamber without autoignition. Either way, you are looking at a uncontrolled (unpredictable) explosion that might hurt someone.
Gasoline and Diesel fuel injectors 'atomize' the fuel into an extremely fine mist - directly into the combustion chamber when needed. This is much more efficient than performing this task with a carburetor.
Diesels run on a fuel with a much higher flash point, and ignited with significantly higher compression ratios (23:1 vs 9:1). When a gas is compressed, it heats up. There are glow-plugs in diesel engines, and are only used to aid in the combustion process at startup when things are cold. After that, the fuel injected into the combustion chamber instantly combusts due to the high temperature of the compressed air.
A model airplane engine is another version of a diesel engine - except it is only two stroke and the glow plug's element is kept glowing by the combustion process.