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ELECTRONIC FUEL INJECTION

ELECTRONIC FUEL INJECTION. DIAGNOSIS AND REPAIR. TOPICS WE ARE GOING TO COVER. GENERAL UNDERSTANDING OF TYPICAL FUEL INJECTION SYSTEMS AND COMPONENTS USED ON TODAYS VEHICLES. TROUBLESHOOTING E.F.I.( ELECTRONIC FUEL INJECTION ) SYSTEMS. STUDY SEVERAL E.F.I. WIRING SCHEMATICS.

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ELECTRONIC FUEL INJECTION

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  1. ELECTRONIC FUEL INJECTION DIAGNOSIS AND REPAIR

  2. TOPICS WE ARE GOING TO COVER • GENERAL UNDERSTANDING OF TYPICAL FUEL INJECTION SYSTEMS AND COMPONENTS USED ON TODAYS VEHICLES. • TROUBLESHOOTING E.F.I.(ELECTRONIC FUELINJECTION) SYSTEMS. • STUDY SEVERAL E.F.I. WIRING SCHEMATICS. • TOOLS USED IN DIAGNOSING FUEL INJECTION RELATED PROBLEMS

  3. COMPONENTS OF A FUEL INJECTED SYSTEM • COMPONENTS OF THE FUEL SYSTEM THAT HAVE ACTUAL MECHANICAL CONNECTION WITH FUEL • FUEL PUMP AND STRAINER • FUEL FILTER • FUEL LINES • FUEL INJECTORS • FUEL PRESSURE REGULATOR

  4. FUEL PUMP AND STRAINER • A FUEL PUMP IS A STEPPER MOTOR THAT PUMPS FUEL TO THE VEHICLES ENGINE. • SOME FUEL PRESSURES CAN EXCEED 65 P.S.I. • FUEL PUMPS ARE ACTIVATED ELECTRONICALLY.

  5. FUEL PUMP AND STRAINER • COMMON TO BE PLACED IN FUEL TANK • COOLED BY THE FUEL IN THE FUEL TANK • NO MAINTENANCE REQUIRED • ALL PUMPS HAVE A CHECK BALL INSIDE TO MAINTAIN FUEL PRESSURE WHILE VEHICLE IS OFF.

  6. FUEL PUMP AND STRAINER • A NORMAL OPERATING FUEL PUMP WILL MAKE A SLIGHT WHINNING NOISE. • FUEL PUMP CAN BE HEARD BY REMOVING THE FUEL TANK FILLER CAP • EXCESSIVE WHINNING CAN BE A SIGN OF FUTURE PUMP FAILURE

  7. FUEL PUMP AND STRAINER • THE IGNITION ON SIGNAL FROM THE IGNITION SWITCH WILL PRIME THE FUEL PUMP, THIS WILL ALLOW THE FUEL SYSTEM TO ACHIEVE ENOUGH FUEL PRESSURE FOR A QUICK ENGINE START

  8. FUEL PUMP AND STRAINER • THE STRAINER IS A FILTER THAT CLIPS TO THE BOTTOM OF THE FUEL PUMP • FILTERS ALL FOREIGN MATERIAL COLLECTED AT THE BOTTOM OF THE FUEL TANK FROM ENTERING FUEL SYSTEM

  9. QUIZ • WHERE IS THE FUEL PUMP USUALLY LOCATED? • HOW IS THE FUEL PUMP ACTIVATED? • WHAT COOLS THE FUEL PUMP? • WHAT PURPOSE DOES THE STRAINER SERVE? • WHAT IS A QUICK WAY TO DETERMINE IF THE FUEL PUMP IS WORKING? • HOW DOES THE FUEL SYSTEM STAY UNDER PRESSURE WHEN THE VEHICLE IS TURNED OFF?

  10. FUEL FILTER • FILTERS CONTAMINANTS (DIRT AND RUST) IN FUEL SYSTEM AS FUEL TRAVELS TO THE ENGINE • CONNECTED IN THE FUEL SUPPLY LINE • ALL FUEL FILTERS HAVE AN INLET AND AN OUTLET • ALL FUEL FILTERS NEED TO BE INSTALLED CORRECTLY, IF INSTALLED BACKWARDS VEHICLE WILL NOT RUN PROPERLY

  11. FUEL FILTER • REPLACEMENT OF A FUEL FILTER IS PART OF REGULAR MAINTENANCE ON A VEHICLE

  12. FUEL FILTER • IF A FUEL FILTER IS NOT REPLACED REGULARLY (DEPENDING ON MANUFACTURER RECOMMENDED REPLACEMENT INTERVAL) IT COULD BECOME CLOGGED AND CAUSE RESTRICTION IN FUEL FLOW

  13. FUEL FILTER

  14. FUEL LINES ARE STEEL, RUBBER AND PLASTIC NYLON MAKE CERTAIN THE REPLACEMENT LINE IS RATED TO HANDLE THE PRESSURES OF THE SYSTEM FUELLINES

  15. ALWAYS USE PRECAUTION WHEN ROUTING FUEL LINES, KEEP THEM AWAY FROM EXHAUST SYSTEM FUEL LINES

  16. QUIZ • IN WHICH LINE IS THE FUEL FILTER SITUATED IN? • HOW COULD A FUEL FILTER BE INSTALLED INCORRECTLY, AND WHAT WOULD HAPPEN TO THE VEHICLE? • WHAT THREE MATERIALS ARE USED IN FUEL LINE FABRICATION? • WHAT PRECAUTIONS SHOULD BE USED WHEN ROUTING FUEL LINES DURING REPLACEMENT?

  17. FUEL INJECTORS FUEL INJECTOR IS AN ELECTRONICALLY CONTROLLED VALVE IT IS SUPPLIED WITH PRESSURIZED FUEL FROM YOUR FUEL PUMP IT OPENS AND CLOSES MANY TIMES PER SECOND

  18. WHEN THE INJECTOR IS ENERGIZED, AN ELECTROMAGNET MOVES A PLUNGER THAT OPENS THE VALVE THIS ALLOWS THE PRESSURIZED FUEL TO SQUIRT OUT THROUGH A TINY NOZZLE. FUEL INJECTORS

  19. FUEL INJECTORS SOME VEHICLE HAVE ONE OR TWO INJECTORS THAT FEED THE ENTIRE SYSTEM, AND OTHERS HAVE AN INJECTOR FOR EACH CYLINDER THE AMOUNT OF FUEL SUPPLIED TO THE ENGINE IS DETERMINED BY THE AMOUNT OF TIME THE INJECTOR IS OPEN (injector on time)

  20. FUEL INJECTORS • T.B.I = THROTTLE BODY INJECTION HAS ONE OR TWO INJECTORS • M.P.I = MULTI PORT INJECTION HAS AN INJECTOR FOR EACH CYLINDER, THE INJECTORS ARE MOUNTED ON A FUEL RAIL.

  21. FUEL INJECTORS • FUEL INJECTORS ARE MOUNTED DIRECTLY IN THE INTAKE MANIFOLD SO THAT THE FUEL SPRAYS DIRECTLY AT THE INTAKE VALVES

  22. FUEL INJECTORS • CARBON CAN CAUSE INJECTORS TO BECOME CLOGGED AND CAUSE ENGINE MISFIRES

  23. FUEL INJECTORS • INJECTOR PURGING CLEANS AWAY CARBON FROM INJECTOR PINTLE AND RESTORES ORIGINAL INJECTOR SPRAY PATTERN WHICH RETURNS ORIGINAL ENGINE PERFORMANCE

  24. FUEL INJECTORS • FUEL INJECTORS CAN BE TESTED WITH A NOID LIGHT, AN OHMETER, OR WITH A SCOPE • INJECTORS MAKE A TICKING SOUND EVERYTIME THEY ARE OPENED AND CLOSED

  25. FUEL PRESSURE REGULATOR • FUEL PRESSURE REGULATOR KEEPS A PREDETERMINED AMOUNT OF PRESSURE IN FUEL RAIL AND RETURNS THE REMAINING FUEL TO THE FUEL TANK

  26. FUEL PRESSURE REGULATOR • PRESSURE IS CONTROLED FROM DIAPHRAGM THAT IS EXPOSED TO MANIFOLD VACCUM

  27. QUIZ • WHAT CAUSES THE INJECTOR TO OPEN? • WHAT HAPPENS WHEN THE INJECTOR OPENS? • WHAT SUBSTANCE IS RESPONSIBLE FOR CLOGGING INJECTORS? • WHAT DOES THE TERM T.B.I. MEAN AND HOW MANY INJECTORS DOES IT HAVE? • WHAT DOES THE TERM M.P.I MEAN AND HOW MANY INJECTORS DOES IT HAVE? • WHERE IS THE INJECTOR LOCATED? • WHAT IS THE PURPOSE OF THE FUEL PRESSURE REGULATOR?

  28. COMPONENTS OF A FUEL INJECTED SYSTEM • ELECTRICAL COMPONENTS OF A FUEL SYSTEM • IGNITION SWITCH • FUEL PUMP RELAY • WIRING AND CONNECTORS • INERTIA SWITCH ( SOME FORD VEHICLES )

  29. IGNITION SWITCH • THE IGNITION SWITCH IS LOCATED IN THE STEERING COLUMN AND IS SWITCHED ON BY TURNING THE KEY • IT IS USUALLY CONNECTED TO THE BACK OF THE KEY CYLINDER

  30. IGNITION SWITCH • THE IGNITION SWITCH GIVES SIGNAL TO THE VEHICLES COMPUTER INFORMING IT OF WHAT DEMAND IS BEING MADE. • DEMANDS THAT ARE MADE TO THE COMPUTER FROM THE IGNITON SWITCH ARE: KEY ON,ENGINE OFF( VOLTAGE TO MOST OF THE VEHICLES ELECTRICAL SYSTEMS START ( CRANKING ) ACTIVATES STARTER KEY OFF ( SWITCH IS OPEN AND CUTS OFF POWER TO MOST ELECTRICAL SYSTEMS ACCESSORY (POWER TO LIMITED COMPONENTS)

  31. IGNITION SWITCH • THERE IS ALWAYS BATTERIE POWER CONNECTED TO ONE SIDE OF THE IGNITION SWITCH • WHEN THE IGNITION KEY IS TURNED BY THE VEHICLES DRIVER THE VOLTAGE SIGNAL TRAVELS THROUGH THE SWITCH TO THE CORRESPONDING CIRCUIT, DEPENDING ON THE DEMAND FROM THE SWITCH. • BY PROBING THE IGNITION SWITCHS CIRCUITS A TEST LIGHT CAN BE USED TO TEST THE PERFORMANCE OF THE IGNITION SWITCH

  32. IGNITION SWITCH • COMMON PROBLEMS THAT CAN OCCUR FROM A DEFECTIVE IGNITION SWITCH * VEHICLE NO START OR CRANK CONDITION * NO POWER IN VEHICLE * MAJOR DRIVEABILITY PROBLEMS * FIRE DAMAGE

  33. IGNITION SWITCH

  34. QUIZ • WHAT DOES THE IGNITON SWITCH DO? • WHERE IS THE IGNITION SWITCH TYPICALLY LOCATED? • WHAT ARE SOME COMMON PROBLEMS THAT CAN OCCUR FROM A MALFUNCTIONING IGNITION SWITCH? • HOW DO YOU TEST AN IGNITION SWITCH? • WHAT VOLTAGE SHOULD YOU SEE AT THE SUPPLY SIDE OF THE IGNITION SWITCH? • WHAT DEMANDS DO THE IGNITION SWITCH MAKE?

  35. FUEL PUMP RELAY • A RELAY IS EQUIVALENT TO A SWITCH. • WHEN GROUNDED, A RELAY CHANGES THE CIRCUIT FROM TO OPEN TO CLOSED • RELAYS ARE COMMONLY FOUND ON WIPER MOTOR CIRCUITS, FAN CIRCUITS, FUEL PUMP CIRCUITS.

  36. FUEL PUMP RELAY • THE IGNITION SWITCH SENDS A SIGNAL THAT ACTIVATES THE FUEL PUMP RELAY • TYPICALLY THE PCM ( POWERTRAIN CONTROL MODULE) RECIEVES THE IGNITION SIGNAL TO EITHER POWER OR GROUND THE FUEL PUMP RELAY WHICH WILL COMPLETE THE FUEL PUMP RELAY CIRCUIT

  37. FUEL PUMP RELAY • FUEL PUMP RELAY IS ON THE SUPPLY SIDE OF THE ELECTRICAL CIRCUIT OF THE FUEL PUMP • THEY ARE LOCATED IN A VARIETY OF LOCATIONS DEPENDING ON THE MAKE AND MODEL OF VEHICLE • SEVERAL COMMON LOCATIONS ARE * UNDER THE HOOD ON THE FIRE WALL * IN THE FUSE PANEL ( UNDER HOOD OR DASH) * IN THE POWER DISTRIBUTION CENTRE

  38. FUEL PUMP RELAY THE OIL PRESSURE SWITCH IS USED FOR START UP IN CASE OF FUEL PUMP RELAY FAILURE(GM)

  39. FUEL PUMP RELAY • WHEN THE KEY IS FIRST TURNED ON, THE IGNITION SWITCH SENDS A SIGNAL TO THE PCM. THE PCM WILL SIGNAL THE RELAY TO ALLOW CURRENT FLOW TO THE FUEL PUMP FOR 3 SECONDS. • THE 3 SECOND PUMP PRIME IS TO ASSIST ON START UP • THE PRIMING WILL BRING FUEL PRESSURE UP TO SPEC. • THIS ALLOWS FOR PROPER FUEL SPRAY FROM THE INJECTORS ON CRANKING TO ENSURE SHORTER CRANKING AND FASTER STARTING

  40. FUEL PUMP RELAY • THE FUEL PUMP RELAY ALLOWS CURRENT FLOW ON CRANKING SIGNAL FROM THE IGNITION SWITCH • BY PROBING THE FUEL PUMP RELAYS PRONGS WITH A TEST LIGHT YOU CAN DIAGNOSE VOLTAGE SIGNALS AT THE RELAY

  41. FUEL PUMP RELAY • IT IS TYPICAL TO HAVE VOLTAGE ON TWO OF THE WIRES IN THE RELAY CIRCUIT. • HOOKING UP A TEST LIGHT TO THE FUEL PUMP RELAY AND MANUALLY GROUNDING THE RELAY YOU WILL DIAGNOSE THE OPERATION OF THE FUEL PUMP RELAY

  42. FUEL PUMP RELAY • WHEN A RELAY IS GROUNDED IT WILL MAKE A SINGLE TICKING NOISE • WHEN TURNING THE KEY ON, YOU CAN HEAR THE FUEL PUMP COME ON FOR SEVERAL SECONDS

  43. QUIZ • WHAT IS A RELAY? • WHAT NOISE WILL A PROPERLY FUNCTIONING RELAY MAKE? • WHAT IS THE BEST WAY TO TEST A RELAY? • WHAT FUNCTION DOES THE RELAY SERVE? • WHERE WOULD YOU USUALLY FIND A RELAY? • WHAT IS A TYPICAL VOLTAGE FOUND AT THE SUPPLY SIDE OF THE RELAY? • WHAT TOOLS CAN BE USED TO TEST A RELAY?

  44. WIRING AND CONNECTORS • WHEN REPAIRING WIRING ALWAYS USE PROPER TECHNIQUE * ALWAYS USE SOLDER * CONNECT THE WIRES IN PROPER FASHION * ALWAYS USE HEAT SHRINK

  45. WIRING AND CONNECTORS • IT IS CRUCIAL TO USE SOLDER ON ALL REPAIRS TO ELIMINATE ANY CHANCE THAT CORROSION DEVELOPS • CORROSION COULD DEVELOP OVER ANY PERIOD OF TIME AND CREATE MAJOR VEHICLE PROBLEMS • CORROSION WILL CREAT A VOLTAGE DROP WHICH WOULD RESULT IN LOWER VOLTAGE AVAILABLE IN THE FUEL CONTROL CIRCUIT • THE LOWER VOLTAGE COULD RESULT IN DRIVEABILITY PROBLEMS OR NO START CONDITIONS

  46. WIRING AND CONNECTORS • FUEL CONTROL WIRING CIRCUIT IS TYPICALLY CONNECTED WITH THE FUEL GAUGE WIRING CIRCUIT. • THE FUEL CONTROL WIRING CIRCUIT IS LOCATED THROUGH OUT THE ENTIRE VEHICLE. • THE FUEL CONTROL CIRCUIT TRAVELS FROM THE BATTERIE, UNDER THE HOOD, INTO THE PASSENGER COMPARTMENT AND INTO THE FUEL TANK

  47. INERTIA SWITCH • IT IS A SWITCH USED ON FORD VEHICLES • IT IS A SAFETY FUEL CUT OFF SWITCH THAT OPENS THE FUEL CONTROL CIRCUIT TO SHUT OFF FUEL SUPPLY FROM THE FUEL TANK DURING AN ACCIDENT

  48. INERTIA SWITCH • VIBRATIONS CAUSE THE SWITCH TO OPEN • THE INERTIA SWITCH CAN CAUSE TRICKY DIAGNOSIS TO TECHNICIANS THAT DO NOT PERFORM THE PROPER DIAGNOIS PROCEDURES • EXCESSIVE STEREO VOLUME CAN CREAT VIBRATRIONS THAT WILL TRIGGER THE INERTIA SWITCH WHICH WILL STALL THE VEHICLE

  49. QUIZ • WHAT COMPANY INVENTED AND USES THE INERTIA SWITCH • WHAT IS THE PURPOSE OF THE INERTIA SWITCH • WHAT TRIGGERS THE INERTIA SWITCH • WHAT SHOULD BE DONE ON ALL WIRING REPAIRS • WHERE IS THE WIRING FOR THE FUEL CONTROL CIRCUIT • WHAT SYSTEM CIRCUIT RUNS ALONG SIDE WITH THE FUEL CONTROL CIRCUIT

  50. DIAGNOSTIC TOOLS • DIAGNOSING TODAYS FUEL INJECTED VEHICLES NEEDS TO BE PERFORMED BY A TRAINED TECHNICIAN WITH EXPERIENCE USING A WIDE VARIETY OF DIFFERENT DIAGNOSTIC TOOLS • DURING DIAGNOSIS IT IS COMMON TO USE MORE THAN ONE TOOL AT A TIME • INFORMATION IS CRITICAL TO ASSIST THE TECHNICIAN ON A PROPER DIAGNOSTIC PROCEDURE

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