203e - Partial: Injectors Flashcards
What three main components make up a fuel injector?
- Nozzle holder
- Nozzle assembly
- Retaining nut
203e pg. 27
What is the role of the intermediate plate in an injector?
Aligns the nozzle assembly with the nozzle holder.
203e pg. 28
What sets the injector cracking pressure?
Spring tension
203e pg. 28
How is an injector internally lubricated and cooled?
By a designed amount of fuel leakage.
203e pg. 28
What two components make up an injector nozzle assembly?
- Nozzle Body
- Needle valve
203e pg. 29
The injector needle valve is opened by _______ pressure and closed by _______ pressure.
Opened by hydraulic pressure.
Closed by spring pressure.
203e pg. 29
Does it require more or less hydraulic pressure to unseat the injector needle valve than it does to hold it open?
Requires more pressure to unseat the needle valve. Less pressure to hold it open.
What type of injectors do direct injection engines use?
Multi-hole injectors.
Opening pressure 2500-5000 psi
203e pg. 29
What cracking pressure variance is acceptable between injectors on an engine?
50psi
What type of injector is used on indirect injection engines?
Pintle
Cone spray pattern.
1400-2500 psi cracking pressure.
203e pg. 30
What is injector nozzle dribble?
When fuel continues to drip out of the injector tip after the injection process has finished.
203e pg. 31
What is used with an injector to seal in combustion gases and promote heat transfer?
Soft metal washer.
203e pg. 32
What could cause high carbon buildup on an injector nozzle?
High heat from:
- engine overloading
- high coolant temperatures
- poor sealing at the washer which limits ability to cool
203e pg. 33
What problems would water in the fuel cause for an injector?
- Corrosion
- Enlarge nozzle holes
- Higher injection pressure as water is more dense than diesel
203e pg. 34
Why are injection lines the same length?
Ensures that an equal volume of fuel is in each line to prevent injection delay from one cylinder to another.
203e pg. 37
