The document discusses different fuel feed systems for petrol engines, including gravity, pressure, vacuum, and pump systems. It describes key components like the fuel tank, fuel pump, fuel filter, carburetor, and inlet manifold. Carburetion is the process that atomizes, vaporizes, and mixes fuel with air to maintain the proper air-fuel ratio for combustion. Precise fuel injection systems provide benefits like increased efficiency and power compared to carbureted systems.

1. Fuel Feed System
In Petrol Engines

2. Types
• Gravity system
• Pressure system
• Vacuum system
• Pump system
• Fuel Injection system

3. Components
Fuel tank Fuel pump Fuel filter
Carburettor Inlet
manifold
Engine
Air Filter

4. Fuel Pump

5. Electrical Fuel Pump
• Starts operating immediately as the ignition switch is switched on
• No need to be situated close to the engine

6. Role of Carburetion
• Atomizes the fuel
• Vaporizes the fuel
• Mixes with air
• Maintains proper A/F ratio
Venturi

7. Stoichiometric Ratio of Gasoline
• It is the theoretical (Chemically correct) A/F ratio by weight required
for proper combustion (14.5:1)
• Lean Mixture
• Here the proportion of fuel is less than the Stoichiometric Ratio
• Rich Mixture
• Here the proportion of fuel is more than the Stoichiometric Ratio
• Cruising of a vehicle needs an A/F ratio about 15:1

8. Requirements of the Engine
• Starting
• Needs rich mixture
• Idling
• Needs rich mixture
• Normal Running
• Lean mixture may be supplied
• Power Range (High power)
• Needs rich mixture

9. Why Idling needs rich mixture
• To compensate the charge dilution, it must be rich
• To overcome the Frictional & Inertial resistances
• Normal Running
• Engine is already designed and tuned to run at the nominal speed
• Power Range
• Requires rich mixture to provide more power
• Prevents overheating

10. Chassis Dynamometer

11. Modified Carburettor (Solex )

12. Types of Carburettors
• Based on draft
• Updraft
• Downdraft
• Sidedraft
• Based on design
• Constant choke carburettors
• Constant vacuum carburettors

13. Why Gasoline Injection?
Increased Volumetric Efficiency
Precise A/F ratio
Reduced Maldistribution of fuel
Better mixing

14. Summary
• Carburetion is the process of atomizing, vaporizing and mixing the
fuel with air
• Mixture which has less than proportion of fuel is less than the
Stoichiometric Ratio is called lean mixture