To which one of the following parts of the diesel engine does the injector deliver fuel?
A. Fuel tank
B. Fuel filter
C. Engine cylinder
D. Governor
Quick Revision Notes
Diesel Injector and Fuel Injection Pump
🔥 Fuel Injector
Delivers fuel to each engine cylinder and sprays it as a fine mist into the combustion chamber.
Purpose: Injection + atomisation
⚙️ Fuel Injection Pump
Meters the required quantity of fuel and supplies it to the injector at high pressure and correct timing.
High-pressure fuel supply
🧩 Inline Pump
Uses a separate plunger-and-barrel pumping element for each engine cylinder.
One element per cylinder
🔄 Distributor Pump
Uses one pumping unit and a rotor to distribute fuel sequentially to all engine cylinders.
Single pump, multiple cylinders
Fuel Flow Sequence
Fuel tankPreliminary filterFeed pumpFine fuel filterInjection pumpInjectorEngine cylinder
- During the compression stroke, only air is compressed in a diesel engine.
- Fuel is injected near the end of compression into high-temperature compressed air.
- Combustion starts due to the high temperature of the compressed air.
Pintle Nozzle
Special Construction
The stem of the nozzle needle is extended to form a pin or pintle that projects through the nozzle mouth.
- Produces a suitable spray even at comparatively low injection pressure.
- Helps avoid weak injection.
- Reduces carbon deposition at the nozzle opening.
Distributor Pump Timing
Internal Cam Ring
The plunger is actuated by an internal cam ring. Rotating the cam ring changes the instant of plunger actuation and therefore changes injection timing.
Exam Key: Rotate cam ring → change injection timing
AMVI Previous-Question Practice
Questions with Answer Reveal
The special feature of a pintle-type nozzle is that it:
A. Has a single hole
B. Has an extended stem to form a pin
C. Is suitable for cold weather
D. Is designed for easy starting
What is used in a diesel engine for spraying fuel at high pressure into the cylinder?
A. Vacuum pump
B. Air pump
C. Fuel injection pump
D. Oil pump
The fuel-injection timing in a distributor-type pump is controlled by:
A. Changing plunger stroke
B. Changing speed of rotor
C. Rotating the cam ring
D. Changing the number of cams on the ring
The advantage of a pintle nozzle is that the pintle prevents ______ in the hole.
A. Formation of oil
B. Formation of steam
C. Deposit of carbon
D. Formation of water
The purpose of the injector provided on a diesel engine is to inject:
A. Lubricant in the cylinder
B. Lubricant in the bearings
C. Fuel in the cylinders
D. Coolant in the cylinder jacket
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FAQ Section
AMVI Preparation FAQs
What is the function of a diesel injector?
It meters, atomises and sprays fuel into the combustion chamber in the required spray pattern.
What is the main feature of a pintle nozzle?
Its needle stem extends outward as a pin or pintle through the nozzle opening.
How is timing adjusted in a distributor pump?
Injection timing is adjusted by rotating the internal cam ring.
Why is the fuel-injection pump important?
It delivers a measured quantity of fuel at high pressure and at the correct time to the injector.
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