Fuel System Principles

1
Fuel System Principles

• St. Cloud Technology Education
• Course General Automotive Service

2
Common Themes

• Convert Chemical Energy to Kinetic Energy
• Increase Power
• Increase Efficiency
• Operate Cleanly

3
Internal Combustion Engines

• Its all in the
• Fuel
• Compression
• Air/Fuel Mixture
• Crankshaft Timing
• Keep it clean (air fuel)
• Sensors

4
(No Transcript)
5
Fuel

• Hydrocarbons!
• Built from combinations of Hydrogen and Carbon
• Energy produced from combustion - the breaking of
  the bonds between Hydrogen and Carbon atoms.
• Organic - Extracted or mined
• Engineered to specifications Chemical
  Engineering
• A Lot of Bang for Your Buck

6
Compression

• More compression higher efficiency and more
  power
• Compression Ratio largest volume of the
  combustion chamber divided by the minimum volume
  of the combustion chamber.
• Gasoline Engines 101
• Increases temperature
• Ignites with spark
• Diesel Engines
• higher ratios
• much higher compression
• Auto-Ignites without spark

7
Stoichiometric Air-Fuel Ratio

• Stoichiometric Air-Fuel Ratio the ratio of air
  to fuel at which exactly all the available oxygen
  and fuel is used completely.
• Gasoline 14.7/1
• All fuels have a target Stoichiometric ratio
• Lean Mixture too much air/too little fuel, runs
  hot!
• Rich Mixture too much fuel/too little air, runs
  cold!

8
Air-Fuel Ratio

• Power
• Efficiency
• Emissions from Exhaust Stream
• Wear Tear

9
Air-Fuel Ratio Extreme Consequences

• Too Lean.
• Too Rich

10
Timing

• Taking Advantage of the Crankshafts Momentum
• Timing of spark can increase efficiency and power
• Combustion of compressed mixture begins to expand
  in perfect step as the piston moves downward.

11
Timing the Spark
12
Fuel Air Filters

• Dirt and Debris KEEP OUT!!!
• Prevent clogging of fuel injectors
• Related to air/fuel ratio.

13
Sensors

• EFI Electronic Fuel Injection
• Multiple sensors gather readings or inputs
• Computer processes the inputs
• Computer makes adjustments
• amount of fuel injected
• timing of when fuel is sprayed into the
  combustion chamber
• Inputs are collected about 100 times/second

14
Part II Components Maintenance