Week 2, Diesel Fuel PPT Flashcards
Diesel fuel requires _____ maintenance compared to gasoline
More
How much pressure is in low pressure diesel fuel systems?
30-70 PSI
How much pressure is in high pressure diesel fuel systems?
3,000-42,000 PSI
Air fuel ratio of diesel fuel systems is _________
14.5:1
What are the three grades of diesel fuels?
1-D
2-D
4-D
Which grade of diesel fuel is preferred for cold weather use and has low emissions?
1-D
Which grade of diesel fuel is most common and has higher heat content?
2-D
Which grade of diesel fuel heats fuel for oil burner furnaces and can be burned in indirect injection engines?
4-D
Diesel fuel’s ignitability or ignition quality
Cetane Number
Adding more cetane to diesel creates
Shorter ignition delay time (faster ignition)
What is a natural part of crude oil?
Sulfur
In 1993, diesel fuel was limited to ______ ppm sulfur content
500
Reducing sulfur content =
Engine longevity
Sulfur and nitrogen molecule that is part of diesel fuel and hard to burn
Aromatic content
- Cetane boosters
- Detergents
- Lubricity additives
- Smoke suppressants
These are all examples of what?
Engine performance enhancers
- De-icing
- Pour point improvers
- Antifoaming
These are all examples of what?
Fuel-handling additives
- Pour point suppressants
- Fuel stabilizers
- Corrosion inhibitors
- Contaminant control
- Biocides
These are all examples of what?
Diesel fuel additives
Quantity of a fuel evaporating at a certain temperature
Volatility
___________ and ___________ are the temperatures at which wax in diesel fuel crystalizes
Pour point; cloud point
_____________ can incorporate relief valve and vacuum relief
Fuel tank cap
Return fuel may need to release _____ and as level drops in tank, air must replace void
Air
____________ can be used to vent the tank when exposed to fire
Thermal plugs
What is the most common type of variable resistance in a sending unit?
Float sensor that moves with fuel level and gauge circuit resistance
Placed just above the bottom of the tank to prevent contamination (heavy duty vehicles use these located at the top of the tank)
Tank pickup
- Soft particles that occur naturally in 2-D diesel fuel
- High heat and oxidation increases content
- 1.5-2 microns in diameter
Asphaltenes
- Most destructive contaminant
- Can seize injectors
Water
What contamination source causes…
- loss of film strength of diesel fuel
- rust
- microorganism growth
Water
__________________ allow draining of water from filter housing
Filter drain valves
_____________ alert operator to water in fuel by either float or electrical conductivity difference
WIF sensors (Water in filter)
Grow in fuel under the right conditions and if fuel is left stagnant (can be treated with biocide)
Bacteria and fungi
What contamination source..
- Solidifies at cold temperature
- Becomes cloudy at 32 degrees F
Wax
When fuel filters are replaced, the system needs to have what done to it?
Air purged from the filter and hand primed
When are hand primers and priming buttons used?
During engine service
What do fuel transfer pumps do?
Moves fuel from tank to high-pressure system
Positive displacement pump with two gears
Gear pump
Process of breaking larger fuel drops into tiny droplets
Atomization
What system uses pressurized engine oil to product high injection pressures and fuel rate control for emission reduction and fuel efficiency?
HEUI systems (Hydraulically activated, Electrically controlled Unit Injector)
Mechanically governed fuel systems have limited injection pressure at low idle because of ___________
Low plunger speed
HEUI systems produce ______________________ independent of engine speed
High-injection pressure
Engine-driven high-pressure oil pump produces up to _______ oil pressure
4,000 PSI
___________ injection is possible and provides a smaller pilot injection before main injection
Split shot
_______ injection is delivered 8-10 degrees before main injection and begins to burn just as main is delivered
Pilot
__________________________ is the most recent development in high-pressure injection systems and is currently used by most diesel engines in production
Common rail fuel injection
What kind of fuel system supplies fuel at injection pressure to nozzle that electrically controls injection event?
Common rail fuel systems
___________ injectors use servo-hydraulic design, allowing electrical solenoid to trigger servo valve and provide a short duration injection
CR (Common Rail)
What kind of fuel injection includes crystals that upon being electrified, expand and provide fuel pressure to spray from the injector?
Piezoceramic Electric Actuators
Piezoceramic electric actuators change ___________ of signal to injector which causes instantaneous change in injector control valve
Polarity
Variable nozzle lift in a fuel injector is possible by doing what?
Varying the voltage applied
Specific gravity is measured in what?
API Units
How do you set the calibration on an injector?
There is often a QR code on the injector itself
