Electronic Fuel Injection Service

Question 1

When should a fuel filter on a return type system be replaced and why?

Answer 1

• every 40,000 km
• restricted filters can lead to stalling and lack of power.

Question 2

When replacing a filter on a return type system, what needs to be done (Include safety protocols)?

Answer 2

• Wear eye + hand protection
• have a fire extinguisher nearby
• MAKE SURE TO depressurize the system before removing filter by removing fuel fuse , relay, or pump connector.
• Have a drain nearby.

Question 3

What is the difference between returnless and return type fuel systems?

Answer 3

Return type: fuel returns to the tank and there is a filter outside of the tank.
Returnless: doesn’t have a filter outside of tank and fuel does not return back to tank (has a PCM).

Question 4

What can a dirty throttle body lead to?

Answer 4

• rough idle, poor performance, and stalling.

Question 5

How do you clean a throttle body, and when do you clean it?

Answer 5

• Remove it if it is easy too - replace the gasket, though.
• spray it with throttle body cleaner.
• clean it when it fills up with crud; additionally, as a maintenance consideration, over 100,000km is when you should clean the throttle body.

Question 6

Why does the throttle body get dirty?

Answer 6

• unburned fuel sticks to the manifold, which builds up carbon, and dust.

Question 7

Why is it important to check for intake air leaks?

Answer 7

It is important to check because a leak could affect the air to fuel ratio which would result in poor performance, engine damage, and fuel inefficiency.
- it could also lead to dust getting in the engine.

Question 8

Where should you check for leaks when doing an intake air leak test (using a smoke machine)?

Answer 8

• hoses, intake gaskets, injectors.

Think of where the engine breathes.

Question 9

What is the downfall of GDI engines? What does it effect on the vehicle?

Answer 9

• carbon deposits are known for building up on the back of the intake valves.
• these carbon build ups can effect volumetric efficiency, idle, and performance on a vehicle.

Question 10

For GDI engines, how can the carbon build up on the intake valves be corrected/cleaned?

Answer 10

• chemical cleaning
• walnut shell blasting
• remove the cylinder head from engine to clean valves.

Question 11

Why do GDI engines have/get carbon deposits?

Answer 11

• blow by gases pass through the intake valves and deposit on them.
• gasoline doesn’t wash the back of the valves (where as multiple port injection does).