The fuel injection system is commonly used in a diesel engine.
In present gasoline injection system is also coming in a petrol engine because following drawbacks of the carburetion.
In present gasoline injection system is also coming in a petrol engine because following drawbacks of the carburetion.
- Non-uniform mixture distribution in multi-cylinder engines.
 - Loss of volumetric efficiency.
 
A gasoline injection system eliminates all these drawbacks.  
The injection of fuel into the SI engine can be done by following methods :
- Direct injection of fuel into the cylinder
 - Injection of fuel close to the inlet valve
 - Injection of fuel into the inlet manifold
 
There are two types of injection system of gasoline systems :
- Continuous Injection: In continuous injection, fuel is continuously injected.
 - Timed Injection: In timed injection, fuel is injected only during induction stroke.
 
Advantages of fuel-injection in SI engines:
- Increased volumetric efficiency
 - Increase thermal efficiency
 - Low exhaust emissions
 - High-quality fuel distribution