IC Engines and Power Plant Lab Lab
LAB 04
Dismantling of Fuel injection system of 6-cylinder CI engine
Lab Supervisor: Engr. Usman Ghani
Submitted by
Name Abdul Qadir
Cmsid 369921
Session ME 13
Section C
Semester 8th
National University of Sciences and technology
School of Mechanical and Manufacturing Engineering (SMME)
1
Objectives:
• To disassemble the fuel injection system of CI engine
• To understand the working and structure of various components of fuel injection system
• Re-assemble the components in their position
Introduction:
The fuel injection system is a critical component of a compression ignition (CI) engine, ensuring efficient fuel
delivery and combustion. In this lab, we disassembled and studied the fuel injection system of a 6-cylinder
inline HINO diesel engine to understand its working and structural components. The system includes key
elements such as fuel injectors, a fuel gallery system, a fuel pump, and connecting tubes, which work together
to deliver fuel at high pressure into the combustion chamber. Other essential components observed include
the fuel filter, high-pressure fuel lines, injector nozzles, and the governor, which regulates fuel supply. This
study provided hands-on experience in analyzing the function and interconnection of these parts, reinforcing
theoretical knowledge with practical insights.
Components of the 6-Cylinder Inline HINO Diesel Engine
1. Fuel Injectors – Deliver atomized fuel directly into the combustion chamber at high pressure to
ensure efficient mixing with air and complete combustion.
2. Fuel Gallery System – A network of passages and rails that distribute fuel evenly to all injectors at
the required pressure.
3. Fuel Pump – Pressurizes the fuel before sending it to the injectors, ensuring the correct amount of
fuel is delivered at the right time.
4. Delivery Tubes – Transport fuel from the pump to the injectors without significant pressure loss.
5. Injector Nozzles – Precisely control the spray pattern and atomization of fuel to optimize
combustion efficiency.
6. Fuel Filter – Removes impurities and contaminants from the fuel before it reaches the pump and
injectors to prevent clogging and wear.
7. Governor – Regulates the amount of fuel supplied to maintain stable engine speed and performance.
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Fuel Injectors
Fuel injectors are responsible for delivering finely atomized fuel into the combustion chamber at high pressure.
They operate based on the pressure developed by the fuel pump. When the fuel pressure exceeds a
predetermined value, it lifts the injector needle off its seat, allowing fuel to spray into the cylinder. The nozzle
shape ensures optimal atomization and mixing with air, leading to efficient combustion. Once the pressure
drops, a return spring forces the needle back to its closed position, stopping the injection process.
Delivery Tubes
The delivery tubes are high-pressure fuel lines that transfer fuel from the gallery system to the injectors. These
tubes are designed to withstand extreme pressures without expanding or losing pressure, ensuring fuel reaches
the injectors in a controlled manner. Additionally, the delivery tubes also route fuel to the governor, which
regulates fuel flow to maintain consistent engine speed and performance under varying load conditions.
Fuel Gallery System
The fuel gallery system consists of interconnected passages that distribute fuel from the pump to the delivery
tubes and injectors. Within the fuel pump, a helix-controlled metering system regulates the amount of fuel
delivered. The helix is a spiral groove on the plunger that rotates within the barrel, adjusting the effective
stroke of the plunger. When the plunger moves upward, fuel is forced into the delivery tubes, and its rotation
determines how much fuel enters the system. This mechanism allows precise fuel metering based on engine
load and speed.
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Fuel Pump
The fuel pump pressurizes the fuel before sending it to the injectors. In a HINO diesel engine, a mechanical
high-pressure fuel pump is driven by the engine camshaft. The pump consists of plungers that move up and
down within barrels, compressing the fuel and pushing it towards the injectors. The timing of fuel delivery is
controlled by the camshaft, ensuring synchronized injection in all cylinders.
Procedure:
Ensure all required tools are available, including wrenches, spanners, and injector pullers. Clean the
surrounding area to facilitate easy removal and inspection of components.
• Disconnect the high-pressure fuel lines (Delivery Tubes) from the injectors.
• Detach the return fuel lines, ensuring they remain undamaged.
• Unscrew the mounting bolts securing the injectors in place.
• Use an injector puller or carefully rock the injectors to remove them without damaging the sealing
surfaces.
• Locate the high-pressure delivery tubes connecting the fuel gallery to the injectors.
• Loosen and remove the high-pressure fittings at both ends.
• Detach and store the tubes in a clean area to prevent damage.
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• Identify the fuel gallery, which distributes fuel to the injectors.
• Disconnect the inlet fuel supply line.
• Unscrew the bolts or clamps securing the gallery system.
• Remove the system carefully, ensuring no damage to the internal passages.
• Locate the fuel pump, typically mounted on the engine block.
• Disconnect any fuel lines attached to the pump.
• Detach the governor linkage
• Unscrew the mounting bolts and carefully remove the fuel pump.
• Re-assemble all components in their position and tighten the screws
Safety Precautions:
• Wear proper PPE, including safety goggles, gloves, and hearing protection.
• Ensure proper ventilation to prevent carbon monoxide buildup.
• Keep hands, clothing, and tools away from moving engine parts.
• Store and handle fuel safely, avoiding spills and ignition sources.
• Use an exhaust extraction system to direct emissions away.
• Never open the radiator cap when the engine is hot.
