Diesel injectors are precision components that must be operating efficiently to ensure proper engine performance. Fuel injectors can cause a whole host of problems that can lead to major engine damage if not diagnosed and replaced or repaired as soon as possible. One big difference between a diesel and a gas engine is the injection process. A lot of cars engines use port injection or a carburetor. Where the port injection system injects fuel just prior to the intake stroke; A carburetor mixes air and fuel long before the air enters the cylinder.