Fuel Injection Systems

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Fuel Injection Systems
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Advantages

• Even fuel/air mixture distribution
• More power
• Less fuel
• Less problems with carburetor ice

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Differences from float carburetors

• Fuel Injection Deposits a continuous flow of
  fuel into the induction system near the intake
  valve just outside of the cylinder.
• Carburetor The correct amount of fuel is metered
  into the airflow.

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Two Types

• Bendix RSA
• Teledyne-Continental

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Bendix Fuel Injection System

• Uses a venturi and air diaphragm to develop a
  fuel metering force.
• Impact tubes sense total pressure of air entering
  the engine. (Dynamic Static)
• Venturi sense its velocity.
• Both combine to move the air diaphragm
  proportionally to the amount of air ingested into
  the engine.

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Fuel Metering Force

• Pressure drop across the orifice in the fuel
  injector nozzles.
• Position of the ball valve in its seat.

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Idle System

• Constant head spring pushes against the air
  diaphragm and forces the ball valve off its seat.
  (at low air flow)
• As air flow increases the air diaphragm moves
  over.

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Idle RPM/Mixture Control

• Limit the amount of air allowed to pass the
  throttle valve.
• Limit the amount of fuel to flow to the discharge
  nozzles.

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Flow Divider

• At idle a spring holds the flow divider valve
  closed to oppose fuel flow until fuel pressure
  off-seats valve.
• Creating down stream pressure for the fuel
  control.
• Provides cut off of fuel at idle cut off.

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The Teledyne-Continental Fuel Injection System

• Meters fuel as a function of engine RPM.
• No Venturi
• Special engine driven pump produces the fuel
  metering pressure. (constant displacement pump)

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Mixture control

• Manual mixture control valve
• Variable selector
• Fuel is bypassed back to the tank.

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Throttle control

• Controls air valve and fuel valve.
• Fuel valve is variable orifice

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Fuel Manifold Valve

• Spider
• Similar to the flow divider of Bendix
• Distributes fuel evenly
• Provides positive shut off at idle cut-off
  position.

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Starting Procedures (Bendix)

• Mixture idle cut-off
• Open throttle 1/8 inch
• Master on
• Boost pump on
• Mixture full rich until indication of fuel flow
• Return mixture to idle cut-off
• Starter engage
• At engine start move mixture to full rich

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Starting (Continental)

• Fuel on
• Crack throttle 1/8 inch
• Mixture full rich
• Boost pump on high
• Fuel flow indicated engage starter
• Bust pump off

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Starting HOT Engine

• Mixture idle cut-off
• Throttle open wide
• Boost pump on high
• Allow fuel to circulate 15-20 siconds
• Boost pump off
• Mixture full rich
• Throttle 1/8
• Engage starter
• Continue normal start.

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Review

• Airflow Sensing/Air Metering Force
• Float Carburetor Venturi
• Bendix Impact Tubes and Venturi
• Teledyne-Continental N/A

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• Fuel Metering force
• Float Pressure Diff. between venturi and float
  chamber
• Bendix Balance between the air and fuel forces
  holds valve off its seat a stabilized amount for
  and given air flow.
• Teledyne-Continental Engine RPM

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• Mixture Control
• Float Back suction, Variable orifice, Needle
  valve at idle.
• Bendix Valve in the fuel control regulates the
  amount of fuel that can flow to main metering
  jet.
• Teledyne-Continental Variable Selector.

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