Fuel Systems

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Fuel Systems
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Components

• Tank
• Filler cap
• Fuel lines
• Fuel filter
• Fuel pump
• Carburetor
• Fuel injection system

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Fuel Tank

• Materials
• Stamped steel
• Aluminum
• Polyethylene plastic
• Baffles
• Filler tube
• Unleaded has small hole
• Leaded has large hole
• Sending unit
• Vent
• Rollover checkvalve

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Carbon Canister

• Fuel vapors are vented into the carbon canister
  which contains active charcoal
• Active charcoal absorbs the hydrocarbons and
  prevents them from evaporating into the
  atmosphere
• During closed loop cruise conditions the carbon
  canister purge valve is commanded open by the
  computer
• This pull the hydrocarbons into the engine where
  they are burnt
• Raw fuel will saturate and destroy a charcoal
  canister
• Capacity 50 grams vapor (equal to 2-3 oz.
  liquid gasoline)

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ECM
Purge Valve
Engine
Vent
Fuel Tank
Charcoal Canister
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Fuel Tank Sending Unit
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Fuel Tank Sending Unit
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Filler Cap

• Non-venting
• Vacuum/pressure relief valve
• Torque limiting mechanism
• Ratchets once pre-determined torque is reached
• Three clicks
• According to Sun Oil research, a missing or
  defective fuel cap can allow as much as 176
  pounds of gasoline vapors (30 gallons) to
  evaporate into the atmosphere each year

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Fuel Lines

• Materials
• Steel
• Aluminum
• Nylon (hard plastic)
• Rubber
• Must be made for use with fuel
• Must be made to withstand adequate pressure
• Fuel injection systems may operate with pressures
  up to 70 PSI
• Fittings
• Compression
• Double flare
• Quick connect type

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Fuel Filter

• Type
• In-tank strainer
• Made of finely woven nylon cloth
• In-line
• Usually used in fuel injection systems
• In-carburetor
• Pleated filter or sintered bronze filter located
  in the fuel inlet of the carburetor

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Fuel Pump

• Mechanical
• Operated off of the camshaft
• Used in carbureted systems
• May have a vapor return line
• Electrical
• Suction type
• May be located anywhere between the tank and the
  fuel metering device
• Pusher type
• Mounted in fuel tank

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Mechanical Pump
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Electric Pump
DO NOT run test electric fuel pumps while they
are out of the tank
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Fuel Pressure Regulator

• Used on fuel injection systems to maintain the
  proper fuel pressure
• During high vacuum cruise conditions the
  regulator will maintain the fuel pressure at a
  lower reading
• During low vacuum WOT conditions the regulator
  will boost fuel pressure

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Fuel Pressure Regulator
Diaphragm
Spring
Manifold Vacuum
Injectors
Seat
Pintle
Fuel Pump
Return Line
Fuel Tank