1. Pressurizes Fuel

• Raises fuel pressure high enough for injectors to spray a fine mist into the combustion chamber.

2. Controls Fuel Timing

• Ensures fuel is injected at the precise moment for optimal combustion.

3. Regulates Fuel Quantity

• Provides the correct amount of fuel based on engine load, speed, and demand.

4. Distributes Fuel to Injectors

• In multi-cylinder engines, it sends fuel to each injector in the correct order.

1. Hard Starting or No Start

• Engine cranks for a long time or fails to start

• Often caused by low fuel pressure or poor timing from the pump

2. Rough Idle or Misfiring

• Engine shakes or runs unevenly

• Fuel delivery is inconsistent or mistimed

3. Loss of Power

• Weak acceleration

• Vehicle struggles under load or going uphill

• Caused by improper fuel pressure or timing

4. Excessive Exhaust Smoke

• Black smoke → too much fuel (rich condition)

• White smoke → unburned fuel (poor injection timing)

• Blue smoke → burning oil (possible internal pump seal leak)

5. Poor Fuel Efficiency

• Engine burns more fuel because timing or delivery is incorrect

6. Engine Stalling

• Cuts out suddenly at idle or when accelerating

• Pump may be failing intermittently

7. Fuel Leaks

• Wet spots around the pump

• Diesel smell near the engine

• Bad seals or cracked housing

8. Loud Knocking or Ticking Sounds

• Poor injection timing causes abnormal combustion

• Often described as a metallic "clatter" in diesel engines

9. Check Engine Light

• Codes related to fuel pressure or timing (e.g., P0087, P0191)

10. Overheating

• Rare, but a failing pump can cause the engine to run hotter due to poor combustion efficiency