Fuel system FORD FESTIVA 1991 Workshop Manual

SBC
Single Bed Converter
SBEC
Single Board Engine Controller
SES
Service Engine Soon
SFI
Sequential (Port) Fuel Injection
SIL
Shift Indicator Light
SIR
Supplemental Inflatable Restraint
SOHC
Single Overhead Cam
SOL or Sol.
Solenoid
SPFI
Sequential Port Fuel Injection
SPK
Spark Control
SPOUT
Spark Output
SRI
Service Reminder Indicator
SRS
Supplemental Restraint System (Air Bag)
STAR
Self-Test Automatic Readout
STO
Self-Test Output
SUB-O
2
Sub Oxygen Sensor
Sw.
Switch
Sys.
System
"T"
TAB
Thermactor Air By-Pass
TAC
Page 13 of 15 MITCHELL 1 ARTICLE - GENERAL INFORMATION Commonly Used Abbreviations
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GASOLINE ENGINE - MECHANICAL TROUBLE SHOOTING
BASIC GASOLINE ENGINE - MECHANICAL TROUBLE SHOOTING CHART
Overheating
Coolant LeakFill/Pressure Test System
A/C Condenser Fins CloggedRemove/Clean Condenser
Radiator Fins CloggedRemove/Clean Radiator
Thermostat Stuck ClosedReplace Thermostat
C l o gge d C o o l in g S yst e m P a ssa ge sClean/Flush Cooling System
Water Pump MalfunctionReplace Water Pump
Fan Clutch MalfunctionReplace Fan Clutch
Retarded Ignition TimingReset Ignition Timing
Cooling Fan MalfunctionTest Cooling Fan/Circuit
Cooling Fan Motor MalfunctionTest Fan Motor
Cooling Fan Relay MalfunctionTest Fan Relay
Faulty Radiator CapReplace Radiator Cap
Broken/Slipping Fan BeltReplace Fan Belt
Restricted ExhaustRepair Exhaust System
Corrosion
Impurities In CoolantClean/Flush System
Coolant Leakage
Damaged hoseReplace Hose
Leaky Water PumpReplace Water Pump
Damaged Radiator SeamReplace/Repair Radiator
Leaky Thermostat CoverReplace Thermostat Cover
Cylinder Head ProblemCheck Head/Head Gasket
Leaky Freeze PlugsReplace Freeze Plugs
Recovery System Inoperative
Loose and/or Defective Radiator CapReplace Radiator Cap
Overflow Tube Clogged and/or LeakingRepair Tube
Recovery Bottle Vent RestrictedClean Vent
No Heater Core Flow
Collapsed Heater HoseReplace Heater Hose
Pl u gge d He a t e r C o r eClean/Replace Heater Core
Faulty Heater ValveReplace Heater Valve
NOTE:This is GENERAL inform ation. This article is not intended to be specific to any unique situation or
individual vehicle configuration. T he purpose of this T rouble Shooting inform ation is to provide a list
of com m on causes to problem sym ptom s. For m odel-specific T rouble Shooting, refer to SUBJECT ,
DIAGNOST IC, or T EST ING articles available in the section(s) you are accessing.
CONDITION & POSSIBLE CAUSECORRECTION
Engine Lopes At Idle
In t ake man ifo l d -t o -h ead l eaksReplace manifold gasket, See
ENGINES
Blown head gasketReplace head gasket, See
ENGINES
Worn timing gears, chain or sprocketReplace gears, chain or
sprocket
Worn camshaft lobesReplace camshaft, See
ENGINES
Overheated engineCheck cooling system, See
COOLING
Blocked crankcase vent valveRemove restriction
Le a kin g E GR va l veRepair leak and/or replace
va l ve
Faulty fuel pumpReplace fuel pump
Engine Has Low Power
Leaking fuel pumpRepair leak and/or replace
fu el p u mp
Excessive piston-to-bore clearanceInstall larger pistons, See
ENGINES
Sticking valves or weak valve springsCheck valve train components,
See ENGINES
Incorrect valve timingReset valve timing, See
ENGINES
Worn camshaft lobesReplace camshaft, See
ENGINES
Blown head gasketReplace head gasket. See
ENGINES.
Clutch slippingAdjust pedal and/or replace
components, See ENGINES
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Engine overheatingCheck cooling system, See
COOLING
Auto. Trans. pressure regulator valve faultyReplace pressure regulator
va l ve
Auto. Trans. fluid level too lowAdd fluid as necessary
Improper vacuum diverter valve operationReplace vacuum diverter valve
Vacuum leaksInspect vacuum system and
repair as required
Leaking piston ringsReplace piston rings, See
ENGINES
Faulty High Speed Operation
Low fuel pump volumeReplace fuel pump
Le a kin g va l ve s o r wo r nReplace valves and/or springs,
See ENGINES
Incorrect valve timingReset valve timing,See
ENGINES
In t ake man ifo l d rest rict edRemove restriction
Worn distributor shaftReplace distributor
Faulty Acceleration
Improper fuel pump strokeRemove pump and reset pump
stroke
Incorrect ignition timingReset ignition timing, See
TUNE-UP
Le a kin g va l ve sReplace valves, See ENGINES
Worn fuel pump diaphragm or pistonReplace diaphragm or piston
In t ake Backfire
Improper ignition timingReset ignition timing, See
TUNE-UP
Faulty accelerator pump dischargeReplace accelerator pump
Improper choke operationCheck choke and adjust as
required
Defective EGR valveReplace EGR valve
Fuel mixture too leanReset air/fuel mixture, See
TUNE-UP
Choke valve initial clearance too largeReset choke valve initial
clearance
Exhaust Backfire
Vacuum leakInspect and repair vacuum
system
Faulty vacuum diverter valveReplace vacuum diverter valve
Faulty choke operationCheck choke and adjust as
required
Exhaust system leakrepair exhaust system leak
Engine Detonation
Ignition timing too far advancedReset ignition timing, See
TUNE-UP
Faulty ignition systemCheck ignition timing, See
TUNE-UP
Spark plugs loose or faultyRetighten or replace plugs
Fuel delivery system cloggedInspect lines, pump and filter
fo r cl o g
EGR valve inoperativeReplace EGR valve
PCV system inoperativeInspect and/or replace hoses
or valve
Vacuum leaksCheck vacuum system and
repair leaks
Excessive combustion chamber depositsRemove built-up deposits
Leaking, sticking or broken valvesInspect and/or replace valves
External Oil Leakage
Fuel pump improperly seated or worn gasketRemove pump, replace gasket
and seat properly
Oil pan gasket broken or pan bentStraighten pan and replace
ga ske t
Timing chain cover gasket brokenReplace timing chain cover
ga ske t
Rear main oil seal wornReplace rear main oil seal
Oil pan drain plug not seated properlyRemove and reinstall drain
plug
Camshaft bearing drain hole blockedRemove restriction
Oil pressure sending switch leakingRemove and reinstall sending
switch
Excessive Oil Consumption
Worn valve stems or guidesReplace stems or guides, See
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ENGINE PERFORMANCE
CARBURETOR TROUBLE SHOOTING:
BASIC COLD START SYMPTOMS TROUBLE SHOOTING CHART
BASIC HOT START SYMPTOMS TROUBLE SHOOTING CHART
BASIC COLD ENGINE DRIVEABILITY SYMPTOMS TROUBLE SHOOTING CHART
Improper connecting rod alignmentRemove and realign
connecting rods
E xc e ssive l y wo r n r in g gr o o ve sReplace pistons, See
ENGINES
Improperly assembled piston pinsRe-assemble pin-to-piston,
See ENGINES
Insufficient ring gap clearanceInstall new rings, See
ENGINES
Engine overheatingCheck cooling system
Incorrect ignition timingRe-adjust ignition timing, See
TUNE-UP
Excessive Exhaust Noise
Leaks at manifold to head, or to pipeReplace manifold or pipe
ga ske t
Exhaust manifold cracked or brokenReplace exhaust manifold, See
ENGINES
NOTE:This is GENERAL inform ation. This article is not intended to be specific to any unique situation or
individual vehicle configuration. T he purpose of this T rouble Shooting inform ation is to provide a list
of com m on causes to problem sym ptom s. For m odel-specific T rouble Shooting, refer to SUBJECT ,
DIAGNOST IC, or T EST ING articles available in the section(s) you are accessing.
CONDITION & POSSIBLE CAUSECORRECTION
Engine Won't Start
Choke not closingCheck choke operation, see
FUEL SYSTEMS
Choke linkage bentCheck linkage, see FUEL
SYSTEM
Engine Starts, Then Dies
Choke vacuum kick setting too wideCheck setting and adjust see,
FUEL SYSTEMS
Fast idle RPM too lowReset RPM to specification,
see TUNE-UP
Fast idle cam index incorrectReset fast idle cam index, see
FUEL SYSTEMS
Vacuum leakInspect vacuum system for
leaks
Low fuel pump outletRepair or replace pump, see
FUEL SYSTEMS
Low carburetor fuel levelCheck float setting see FUEL
SYSTEM
Engine Quits Under Load
Choke vacuum kick setting incorrectReset vacuum kick setting,see
FUEL SYSTEMS
Fast idle cam index incorrectReset fast idle cam index, see
FUEL SYSTEM
Incorrect hot fast idle speed RPMReset fast idle RPM, see
TUNE-UP
Engine Starts, Runs Up, Then Idles, Slowly With Black Smoke
Choke vacuum kick set too narrowReset vacuum kick, see FUEL
SYSTEMS
Fast idle cam index incorrectReset fast idle cam index, see
FUEL SYSTEMS
Hot fast idle RPM too lowReset fast idle RPM, see
TUNE-UP
CONDITION & POSSIBLE CAUSECORRECTION
Engine Won't Start
Engine floodedAllow fuel to evaporate
CONDITION & POSSIBLE CAUSECORRECTION
Engine Stalls in Gear
Choke vacuum kick setting incorrectReset choke vacuum kick, see
FUEL SYSTEMS
Fast idle RPM incorrectReset fast idle RPM, see
TUNE-UP
Fast idle cam index incorrectReset fast idle cam see FUEL
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BASIC WARM ENGINE DRIVEABILITY SYMPTOMS TROUBLE SHOOTING CHART
DIESEL ENGINE TROUBLE SHOOTING
BASIC DIESEL ENGINE TROUBLE SHOOTING CHART
SYSTEMS
Acceleration Sag or Stall
Defective choke control switchReplace choke control switch
Choke vacuum kick setting incorrectReset choke vacuum kick see,
FUEL SYSTEMS
Float level incorrect (too low)Adjust float level, FUEL
SYSTEMS
Accelerator pump defectiveRepair or replace pump see
FUEL SYSTEMS
Secondary throttles not closedInspect lockout adjustment,
see FUEL SYSTEMS
Sag or Stall After Warmup
Defective choke control switchReplace choke control switch,
see FUEL SYSTEMS
Defective accelerator pumpReplace pump, see FUEL
SYSTEMS
Float level incorrect (too low)Adjust float level, see FUEL
SYSTEMS
Backfiring & Black Smoke
Plugged heat crossover systemRemove restriction
CONDITION & POSSIBLE CAUSECORRECTION
Hesitation With Small Amount of Gas Pedal Movement
Vacuum leakInspect vacuum lines
Accelerator pump weak or inoperableReplace pump, see FUEL
SYSTEMS
Float level setting too lowReset float level, see,FUEL
SYSTEMS
Metering rods sticking or bindingInspect and/or replace rods,
see FUEL SYSTEMS
Carburetor idle or transfer system pluggedInspect system and remove
restriction
Frozen or binding heated air inletInspect heated air door for
binding
Hesitation With Heavy Gas Pedal Movement
Defective accelerator pumpReplace pump, see FUEL
SYSTEMS
Metering rod carrier sticking or bindingRemove restriction
Large vacuum leakInspect vacuum system and
repair leak
Float level setting too lowReset float level, see FUEL
SYSTEMS
Defective fuel pump, lines or filterInspect pump, lines and filter
Air door setting incorrectAdjust air door setting, see
FUEL
NOTE:This is GENERAL inform ation. This article is not intended to be specific to any unique situation or
individual vehicle configuration. T he purpose of this T rouble Shooting inform ation is to provide a list
of com m on causes to problem sym ptom s. For m odel-specific T rouble Shooting, refer to SUBJECT ,
DIAGNOST IC, or T EST ING articles available in the section(s) you are accessing.
NOTE:Diesel engines m echanical diagnosis is the sam e as gasoline engines for item s such as noisy valves,
bearings, pistons, etc. T he following trouble shooting covers only item s pertaining to diesel engines.
CONDITION & POSSIBLE CAUSECORRECTION
Engine Won't Crank
Bad battery connections or dead batteriesCheck connections and/or
replace batteries
Bad starter connections or bad starterCheck connections and/or
replace starter
Engine Cranks Slowly, Won't Start
Bad battery connections or dead batteriesCheck connections and/or
replace batteries
Engine oil too heavyReplace engine oil
Engine Cranks Normally, But Will Not Start
Glow plugs not functioningCheck glow plug system, see
FUEL SYSTEMS
Glow plug control not functioningCheck controller, see FUEL
SYSTEMS
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Fuel not injected into cylindersCheck fuel injectors, see FUEL
SYSTEMS
No fuel to injection pumpCheck fuel delivery system
Fuel filter blockedReplace fuel filter
Fuel tank filter blockedReplace fuel tank filter
Fuel pump not operatingCheck pump operation and/or
replace pump
Fuel return system blockedInspect system and remove
restriction
No voltage to fuel solenoidCheck solenoid and
connections
Incorrect or contaminated fuelReplace fuel
Incorrect injection pump timingRe-adjust pump timing, see
FUEL SYSTEMS
Low compressionCheck valves, pistons, rings,
see ENGINES
Injection pump malfunctionInspect and/or replace
injection pump
Engine Starts, Won't Idle
Incorrect slow idle adjustmentReset idle adjustment, see
TUNE-UP
Fast idle solenoid malfunctioningCheck solenoid and
connections
Fuel return system blockedCheck system and remove
restrictions
Glow plugs go off too soonSee glow plug diagnosis in
FUEL SYSTEMS
Injection pump timing incorrectReset pump timing, see FUEL
SYSTEMS
No fuel to injection pumpCheck fuel delivery system
Incorrect or contaminated fuelReplace fuel
Low compressionCheck valves, piston, rings, see
ENGINES
Injection pump malfunctionReplace injection pump, see
FUEL SYSTEMS
Fuel solenoid closes in RUN positionCheck solenoid and
connections
Engines Starts/Idles Rough W/out Smoke or Noise
Incorrect slow idle adjustmentReset slow idle, see TUNE-UP
Injection line fuel leaksCheck lines and connections
Fuel return system blockedCheck lines and connections
Air in fuel systemBleed air from system
Incorrect or contaminated fuelReplace fuel
Injector nozzle malfunctionCheck nozzles, see FUEL
SYSTEMS
Engines Starts and Idles Rough W/out Smoke or Noise, But Clears After Warm-Up
Injection pump timing incorrectReset pump timing, see FUEL
SYSTEMS
Engine not fully broken inPu t mo re mil es o n en gin e
Air in systemBleed air from system
Injector nozzle malfunctionCheck nozzles, see FUEL
SYSTEMS
Engine Idles Correctly, Misfires Above Idle
Bl o cked fu el fil t erReplace fuel filter
Injection pump timing incorrectReset pump timing, see FUEL
SYSTEMS
Incorrect or contaminated fuelReplace fuel
Engine Won't Return To Idle
Fast idle adjustment incorrectReset fast idle, see TUNE-UP
Internal injection pump malfunctionReplace injection pump, see
FUEL SYSTEMS
External linkage bindingCheck linkage and remove
binding
Fuel Leaks On Ground
Loose or broken fuel lineCheck lines and connections
Internal injection pump seal leakReplace injection pump, see
FUEL SYSTEMS
Cylinder Knocking Noise
Injector nozzles sticking openTest injectors, see FUEL
SYSTEMS
Very low nozzle opening pressureTest injectors and/or replace
Loss of Engine Power
Restricted air intakeRemove restriction
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VACUUM PUMP DIAGNOSIS
FUEL INJECTION TROUBLE SHOOTING
BASIC FUEL INJECTION TROUBLE SHOOTING CHART
EGR valve malfunctionReplace EGR valve
Blocked or damaged exhaust systemRemove restriction and/or
replace components
Blocked fuel tank filterReplace filter
Restricted fuel filterRemove restriction and/or
replace filter
Block vent in gas capRemove restriction and/or
replace cap
Tank-to-injection pump fuel supply blockedCheck fuel lines and
connections
Blocked fuel return systemRemove restriction
Incorrect or contaminated fuelReplace fuel
Blocked injector nozzlesCheck nozzle for blockage, see
FUEL SYSTEMS
Low compressionCheck valves, rings, pistons,
see ENGINES
Loud Engine Noise With Black Smoke
Basic timing incorrectReset timing, see FUEL
SYSTEMS
EGR valve malfunctionReplace EGR valve
Internal injection pump malfunctionReplace injection pump, see
FUEL SYSTEMS
Incorrect injector pump housing pressureCheck pressure, see FUEL
SYSTEMS
Engine Overheating
Cooling system leaksCheck cooling system and
repair leaks
Belt slipping or damagedCheck tension and/or replace
belt
Thermostat stuck closedRemove and replace
thermostat, see ENGINE
COOLING
Head gasket leakingReplace head gasket
Oil Light on at Idle
Low oil pump pressureCheck oil pump operation, see
ENGINES
Oil cooler or line restrictedRemove restriction and/or
replace cooler
Engine Won't Shut Off
Injector pump fuel solenoid does not return fuel valve to OFF positionRemove and check solenoid
and replace if needed
CONDITION & POSSIBLE CAUSECORRECTION
Excessive Noise
Loose pump-to-drive assembly screwsTighten screws
Loose tube on pump assemblyTighten tube
Valves not functioning properlyReplace valves
Oil Leakage
Loose end plugTighten end plug
Bad seal crimpRemove and re-crimp seal
NOTE:This is GENERAL inform ation. This article is not intended to be specific to any unique situation or
individual vehicle configuration. T he purpose of this T rouble Shooting inform ation is to provide a list
of com m on causes to problem sym ptom s. For m odel-specific T rouble Shooting, refer to SUBJECT ,
DIAGNOST IC, or T EST ING articles available in the section(s) you are accessing.
CONDITION & POSSIBLE CAUSECORRECTION
Engine Won't Start (Cranks Normally)
Cold start valve inoperativeTest valve and circuit
Poor connection;vacuum or wiringCheck vacuum and electrical
connections
Contaminated fuelTest fuel for water or alcohol
Defective fuel pump relay or circuitTest relay and wiring
Battery too lowCharge and test battery
Low fuel pressureTest pressure regulator and
fuel pump, check for restricted
lines and filters
No distributor reference pulsesRepair ignition system as
necessary
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IGNITION SYSTEM TROUBLE SHOOTING
Open coolant temperature sensor circuitTest sensor and wiring
Shorted W.O.T. switch in T.P.S.Disconnect W.O.T. switch,
engine should start
Defective ECMReplace ECM
Fuel tank residual pressure valve leaksTest for fuel pressure drop
after shut down
Hard Starting
Disconnected hot air tube to air cleanerReconnect tube and test
control valve
Defective Idle Air Control (IAC) valveTest valve operation and
circuit
Shorted, open or misadjusted T.P.S.Test and adjust or replace
T.P.S.
EGR valve openTest EGR valve and control
circuit
Poor Oxygen sensor signalTest for shorted or circuit
Incorrect mixture from PCV systemTest PCV for flow, check
sealing of oil filter cap
Poor High Speed Operation
Low fuel pump volumeFaulty pump or restricted fuel
lines or filters
Poor MAP sensor signalTest MAP sensor, vacuum
hose and wiring
Poor Oxygen sensor signalTest for shorted or open
sensor or circuit
Open coolant temperature sensor circuitTest sensor and wiring
Faulty ignition operationCheck wires for cracks or poor
con- nections, test secondary
voltage with oscilloscope
Contaminated fuelTest fuel for water or alcohol
Intermittent ECM groundTest ECM ground connection
for resistance
Restricted air cleanerReplace air cleaner
Restricted exhaust systemTest for exhaust manifold back
pressure
Poor MAF sensor signalCheck leakage between sensor
and manifold
Poor VSS signalIf tester for ALCL hook-up is
available check that VSS
reading matches speedometer
Ping or Knock on Acceleration
Poor Knock sensor signalTest for shorted or open
sensor or circuit
Poor Baro sensor signalTest for shorted or open
sensor or circuit
Improper ignition timingSee VEHICLE EMISSION
CONTROL LABEL (where
applicable)
Check for engine overheating problemsLow coolant, loose belts or
electric cooling fan inoperative
NOTE:For additional electronic fuel injection trouble shooting inform ation, see the appropriate article in the
ENGINE PERFORMANCE section (not all vehicles have Com puter Engine Control articles). Inform ation
is provided there for diagnosing fuel system problem s on vehicles with electronic fuel injection.
NOTE:This is GENERAL inform ation. This article is not intended to be specific to any unique situation or
individual vehicle configuration. T he purpose of this T rouble Shooting inform ation is to provide a list
of com m on causes to problem sym ptom s. For m odel-specific T rouble Shooting, refer to SUBJECT ,
DIAGNOST IC, or T EST ING articles available in the section(s) you are accessing.
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TUNE-UP TROUBLE SHOOTING - GAS ENGINE VEHICLES
BASIC SPARK PLUG TROUBLE SHOOTING CHARTS
Faulty solenoid switch, switch connections or relayCheck all wiring between
relay and solenoid or replace
relay or solenoid as necessary
Broken lead or loose soldered connectionsRepair wire or wire
connections as necessary
Solenoid Plunger Vibrates When Switch is Engaged
Weak batteryCharge or replace battery as
necessary
Solenoid contacts corrodedClean contacts or replace
solenoid
Faulty wiringCheck all wiring leading to
solenoid
Broken connections inside switch coverRepair connections or replace
solenoid
Open hold-in wireReplace solenoid
Low Current Draw
Worn brushes or weakReplace brushes or brush
springs as necessary
High Pitched Whine During Cranking Before Engine Fires but Engine Fires and Cranks Normally
Distance too great between starter pinion and flywheelAlign starter or check that
correct starter and flywheel
are being used
High Pitched Whine After Engine Fires With Key released. Engine Fires and Cranks Normally
Distance too small between starter pinion and flywheelFlywheel runout contributes
to the intermittent nature
NOTE:This is GENERAL inform ation. This article is not intended to be specific to any unique situation or
individual vehicle configuration. T he purpose of this T rouble Shooting inform ation is to provide a list
of com m on causes to problem sym ptom s. For m odel-specific T rouble Shooting, refer to SUBJECT ,
DIAGNOST IC, or T EST ING articles available in the section(s) you are accessing.
CONDITION & POSSIBLE CAUSECORRECTION
Normal Spark Plug Condition
Light Tan or Gray depositsNo Action
Electrode not burned or fouledNo Action
Gap tolerance not changedNo Action
Cold Fouling or Carbon Deposits
Overrich air/fuel mixtureAdjust air/fuel mixture, see
ENGINE PERFORMANCE
section
Faulty chokeReplace choke assembly, see
ENGINE PERFORMANCE
section
Clogged air filterClean and/or replace air filter
Incorrect idle speed or dirty carburetorReset idle speed and/ or clean
carburetor
Faulty ignition wiresReplace ignition wiring
Prolonged operation at idleShut engine off during long
idle
Sticking valves or worn valve guide sealsCheck valve train
Wet Fouling or Oil Deposits
Worn rings and pistonsInstall new rings and pistons
Excessive cylinder wearRebore or replace block
Excessive valve guide clearanceWorn or loose bearing
Gap Bridged
Deposits in combustion chamber becoming fused to electrodeClean combustion chamber of
deposits
Blistered Electrode
Engine overheatingCheck cooling system
Wrong type of fuelReplace with correct fuel
Loose spark plugsRetighten spark plugs
Over-advanced ignition timingReset ignition timing see
ENGINE PERFORMANCE
Pre-Ignition or Melted Electrodes
Incorrect type of fuelReplace with correct fuel
Incorrect ignition timingReset ignition timing see
ENGINE PERFORMANCE
Burned valvesReplace valves
Engine OverheatingCheck cooling system
Wrong type of spark plug, too hotReplace with correct spark
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BASIC ELECTRONIC IGNITION TROUBLE SHOOTING CHARTS
BASIC ELECTRONIC IGNITION TROUBLE SHOOTING CHARTS - USING OSCILLOSCOPE PATTERNS
plug, see ENGINE
PERFORMANCE
Chipped Insulators
Severe detonationCheck for over-advanced
timing or combustion
Improper gapping procedureRe-gap spark plugs
Rust Colored Deposits
Additives in unleaded fuelTry different fuel brand
Water In Combustion Chamber
Blown head gasket or cracked headRepair or replace head or head
ga ske t
NOTE:Before diagnosing an electronic ignition system , ensure that all wiring is connected properly between
distributor, wiring connector and spark plugs. Ignition problem will show up either as: Engine Will Not
Start or Engine Runs Rough.
CONDITION & POSSIBLE CAUSECORRECTION
Engine Won't Start
Open circuit between distributor and bulkhead connectorRepair circuit
Open circuit between bulkhead connector and ignition switchRepair circuit
Open circuit between ignition switch and starter solenoidRepair circuit
Engine Runs Rough
Fuel lines leaking or cloggedTigh t e n fit t in g, r e mo ve
restriction
Initial timing incorrectReset ignition timing see
ENGINE PERFORMANCE
Centrifugal advance malfunctionRepair distributor advance
Defective spark plugs or wiringReplace plugs or plug wiring
Component Failure
Spark arc-over on cap, rotor or coilReplace cap, rotor or or coil
Defective pick-up coilReplace pick-up coil
Defective ignition coilReplace ignition coil
Defective vacuum unitReplace vacuum unit
Defective control moduleReplace control module
CONDITION & POSSIBLE CAUSECORRECTION
Firing Voltage Lines are the Same, but Abnormally High
Retarded ignition timingReset ignition timing, see
ENGINE PERFORMANCE
section
Fuel mixture too leanReadjust carburetor, see
ENGINE PERFORMANCE
High resistance in coil wireReplace coil wire
Corrosion in coil tower terminalClean and/or replace coil
Corrosion in distributor coil terminalClean and/or replace
distributor cap
Firing Voltage Lines are the Same but Abnormally Low
Fuel mixture too richReadjust carburetor, see
ENGINE PERFORMANCE
Breaks in coil wire causing arcingReplace coil wire
Cracked coil tower causing arcingReplace coil
Low coil outputReplace coil
Low engine compressionDetermine cause and repair
One or More, But Not All Firing Voltage Lines are Higher Than Others
Carburetor idle mixture not balancedReadjust carburetor, see
ENGINE PERFORMANCE
EGR valve stuck openClean and/or replace valve
High resistance in spark plug wiresReplace spark plug wires
Cracked or broken spark plug insulatorReplace spark plugs
Intake vacuum leakRepair leak
Defective spark plugsReplace spark plugs
Corroded spark plug terminalsReplace spark plugs
One or More, But Not All Firing Voltage Lines Are Lower Than Others
Curb idle mixture not balancedReadjust carburetor, see
ENGINE PERFORMANCE
Breaks in plug wiresReplace plug wires causing
arcing
Cracked coil tower causing arcingReplace coil
Low compressionDetermine cause and repair
Defective spark plugsReplace spark plugs
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