FUEL INJECTION SYSTEM OPERATIONBy Melodias Ben Hur Jr.
FUEL INJECTION TYPES THROTTLE BODY INJECTION (TBI)INJECTED ABOVE
THROTTLE PLATESSINGLE INJECTORCENTRAL PORT INJECTION (CFI)INJECTED
ABOVE THROTTLE PLATESUSUALLY MORE THAN ONE INJECTORPORT FUEL
INJECTION (PFI)INJECTORS IN INTAKE RUNNERS
TBI UNIT(SOMETIMES CALLED CFI)FIRST STEP FROM CARBURETORSSOME
CARB CHARACTERISTICSLOW PRESSUREMOVEABLE PINTLEPRESSURE IS
REGULATEDSERVICEABLEFIG 6-40 CLASS
LOW PRESSURE SYSTEM
FUEL INLET AND OUTLET
LOW PRESSURE FUEL INJECTOR13-16 PSITWO O-RINGSBALL PINTLEUSED ON
TBI AND CFI SYSTEMSMESH SCREENEASY TO REPLACE
TWO INJECTOR SYSTEM
PORT FUEL INJECTIONINJECTS AT EACH CYLINDERHIGHER PRESSUREFED
OFF OF FUEL RAILMORE EFFICIENT
OPERATIONMODESMULTI-PORTSEQUENTIAL
PORT FUEL INJECTION
CENTRAL POINT INJECTIONGM SYSTEMINJECTOR LOCATED IN LOWER HALF
OF INTAKE MANIFOLDPOPPET VALVESHIGH PRESSURE 60 PSIFIG 6-49
CLASS
CONTINUOUS INJECTIONSPRAYS ALL THE TIMEMIXTURE CONTROL UNITFUEL
DISTRIBUTORCONTROL PRESSURE REGULATOR
FUEL PRESSURE REGULATORUsed on TBI systems Provides constant
fuel supplyFuel pressure on one sideFuel pressure opens regulator
under a certain pressure.Spring is calibrated
INJECTION SYSTEM SERVICECHAPTER 6LAB MANUAL
SYSTEM CHECKSADEQUATE AIR SUPPLYPRESSURIZED FUEL SUPPLYADEQUATE
TRIGGER SIGNALNO VACUUM LEAKSGOOD IGNITION SYSTEMGOOD ENGINE
MECHANICAL GOOD FUEL QUALITYPCM OPERATION
FUEL DELIVERYFuel Pump noisesDoes fuel pump run at all?Fuel
filter condition?Connections to fuel pump
