1. Fuel Pressure Regulator: A faulty fuel pressure regulator can cause an excessively rich fuel mixture, leading to unburned fuel exiting the exhaust manifold.
2. Fuel Injectors: Leaking or faulty fuel injectors can deliver an excessive amount of fuel, resulting in raw fuel in the exhaust.
3. Oxygen Sensor: A malfunctioning oxygen sensor can provide incorrect feedback to the engine control unit (ECU), causing incorrect fuel adjustments and leading to raw fuel in the exhaust.
4. Spark Plugs: Worn-out or faulty spark plugs can cause inefficient combustion, resulting in unburned fuel in the exhaust system.
5. Catalytic Converter: A clogged or damaged catalytic converter can restrict the flow of exhaust gases, causing raw fuel to be pushed out through the exhaust manifold.
6. Engine Wear: Excessive wear on the engine's piston rings or cylinder walls can lead to poor compression, resulting in incomplete combustion and raw fuel in the exhaust.
7. Incorrect Air-Fuel Mixture: A lean air-fuel mixture (too much air, not enough fuel) can cause raw fuel to be expelled through the exhaust manifold due to incomplete combustion.
8. Ignition Timing: Incorrect ignition timing can disrupt the combustion process and lead to raw fuel exiting the exhaust manifold.
It is recommended to have a qualified mechanic diagnose and address the root cause of the problem to ensure proper engine operation and prevent potential damage to the exhaust system and other engine components.
