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FUEL INJECTION FUEL INJECTION SYSTEM OPERATIONSYSTEM OPERATION

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FUEL INJECTION TYPES FUEL INJECTION TYPES THROTTLE BODY INJECTION (TBI)

– INJECTED ABOVE THROTTLE PLATES– SINGLE INJECTOR

CENTRAL PORT INJECTION (CFI)– INJECTED ABOVE THROTTLE PLATES– USUALLY MORE THAN ONE INJECTOR

PORT FUEL INJECTION (PFI)– INJECTORS IN INTAKE RUNNERS

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TBI UNITTBI UNIT(SOMETIMES CALLED CFI)(SOMETIMES CALLED CFI)

FIRST STEP FROM CARBURETORS

SOME CARB CHARACTERISTICS

LOW PRESSURE MOVEABLE PINTLE PRESSURE IS

REGULATED SERVICEABLE

FIG 6-40 CLASS

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LOW PRESSURE LOW PRESSURE SYSTEMSYSTEM

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FUEL INLET AND FUEL INLET AND OUTLETOUTLET

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LOW PRESSURE FUEL LOW PRESSURE FUEL INJECTORINJECTOR

13-16 PSI TWO O-RINGS BALL PINTLE USED ON TBI

AND CFI SYSTEMS

MESH SCREEN EASY TO

REPLACE

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TWO INJECTOR SYSTEMTWO INJECTOR SYSTEM

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PORT FUELPORT FUEL INJECTION INJECTION

INJECTS AT EACH CYLINDER

HIGHER PRESSURE

FED OFF OF FUEL RAIL

MORE EFFICIENT OPERATION

MODES– MULTI-PORT– SEQUENTIAL

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PORT FUEL INJECTIONPORT FUEL INJECTION

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CENTRAL POINT CENTRAL POINT INJECTIONINJECTION

GM SYSTEM INJECTOR

LOCATED IN LOWER HALF OF INTAKE MANIFOLD

POPPET VALVES HIGH PRESSURE

60 PSI

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CONTINUOUSCONTINUOUS INJECTION INJECTION

SPRAYS ALL THE TIME MIXTURE CONTROL UNIT FUEL DISTRIBUTOR CONTROL PRESSURE REGULATOR

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FUEL PRESSURE FUEL PRESSURE REGULATORREGULATOR

Used on TBI systems

Provides constant fuel supply

Fuel pressure on one side

Fuel pressure opens regulator under a certain pressure.

Spring is calibrated

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INJECTION SYSTEM INJECTION SYSTEM SERVICESERVICE

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SYSTEM CHECKSSYSTEM CHECKS ADEQUATE AIR SUPPLY PRESSURIZED FUEL SUPPLY ADEQUATE TRIGGER SIGNAL NO VACUUM LEAKS GOOD IGNITION SYSTEM GOOD ENGINE MECHANICAL GOOD FUEL QUALITY PCM OPERATION

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FUEL DELIVERYFUEL DELIVERY Fuel Pump

noises Does fuel pump

run at all? Fuel filter

condition? Connections to

fuel pump

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COMPONENT CHECKSCOMPONENT CHECKS AIR INDUCTION AIR FLOW

SENSORS THROTTLE BODY FUEL SYSTEM

CHECKS FUEL DELIVERY INJECTOR CHECKS INJECTOR

CLEANING

6-61 LAB

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INERTIA SWITCHINERTIA SWITCH

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INJECTOR TESTSINJECTOR TESTS ELECTRICAL OPERATION

– VOLTAGE SIGNALS– SCOPE TESTING

MECHANICIAL OPERATION– PINTLE OPERATION– BALANCE TEST– FLOW