1. Fuel pump
2. Fuel filter
3. Throttle body
4. Fuel injector
5. Fuel pressure regulator6. Special tool
(Fuel pressure gauge &
3-way joint)
7. Fuel feed line
8. Fuel return line
6-100 ENGINE GENERAL INFORMATION AND DIAGNOSIS (TBI FOR G10)
TABLE B-3 FUEL PRESSURE CHECK
INSPECTION
STEPACTIONYESNO
1Check Fuel Pressure (Refer to Section 6E1 for details).
1) Release fuel pressure from fuel feed line.
2) Install fuel pressure gauge.
3) Check fuel pressure by repeating ignition switch
ON and OFF. See Fig. 1.
Is fuel pressure then 160 – 210 kPa (1.6 – 2.1 kg / cm
2,
22.7 – 29.9 psi)?
Go to Step 2.Go to Step 4.
2Is 90 kPa (0.9 kg / cm2, 12.8 psi) or higher fuel
pressure retained for 1 minute after fuel pump is
stopped at Step 1?Normal fuel pressure.Go to Step 3.
31) Start engine and warm it up to normal operating
temperature.
2) Keep it running at specified idle speed.
Is fuel pressure then within 90 – 140 kPa
(0.9 – 1.4 kg / cm
2, 12.8 – 20.0 psi)?
Normal fuel pressure.Clogged vacuum
passage for fuel
pressure regulator
or
Faulty fuel pressure
regulator.
4Is there fuel leakage from fuel feed line hose, pipe or
their joint?Fuel leakage from
hose, pipe or joint.Go to Step 10.
5Was fuel pressure higher than specification in Step 1?Go to Step 6.Go to Step 7.
61) Disconnect fuel return hose from throttle body and
connect new return hose to it.
2) Insert the other end of new return hose into
approved gasoline container.
3) Operate fuel pump.
Is specified fuel pressure obtained then?Restricted fuel return
hose or pipe.Faulty fuel pressure
regulator.
7Was no fuel pressure supplied in Step 1?Go to Step 8.Go to Step 9.
ENGINE GENERAL INFORMATION AND DIAGNOSIS (TBI FOR G10) 6-101
Fig. 1 for Step 1
1. Fuel pressure gauge & 3way joint
STEPACTIONYESNO
8With fuel pump operated and fuel return hose
blocked by pinching it, is fuel pressure applied?Faulty fuel pressure
regulator.Shortage of fuel or fuel
pump or its circuit
defective (refer to B-2
FUEL PUMP ANDITS
CIRCUIT CHECK).
91) Operate fuel pump.
2) With fuel return hose blocked by pinching it, check
fuel pressure.
Is it 450 kPa (4.5 kg / cm
2, 63.9 psi) or more?
Faulty fuel pressure
regulator.Clogged fuel filter,
Restricted fuel feed
hose or pipe,
Faulty fuel pump or
Fuel leakage from
hose connection in
fuel tank.
101) Disconnect fuel return hose from throttle body and
connect new return hose to it.
2) Insert the other end of new return hose into
approved gasoline container.
3) Check again if specified pressure is retained.
While doing so, does fuel come out of return hose?Faulty fuel pressure
regulator.Fuel leakage from
injector,
Fuel leakage from
between injector
and throttle body,
Faulty fuel pump
(faulty check valve
in fuel pump) or
Fuel leakage from
fuel pressure
regulator
diaphragm.
ENGINE GENERAL INFORMATION AND DIAGNOSIS (SFI FOR G13) 6-1-23
ConditionPossible Cause]Referring Item
Low oil pressureImproper oil viscosity
Malfunctioning oil pressure switch
Clogged oil strainer
Functional deterioration of oil pump
Worn oil pump relief valve
Excessive clearance in various sliding partsEngine oil and oil filter change in
Section 0B
Oil pressure switch inspection in
Section 8
Oil pan and oil pump strainer
cleaning in Section 6A1
Oil pump in Section 6A1
Oil pump in Section 6A1
Engine noise
Note: Before
checking mechanical
noise, make sure
that:
Specified spark
plug in used.
Specified fuel is
used.Valve noise
Improper valve lash
Worn valve stem and guide
Weak or broken valve spring
Warped or bent valve
Piston, ring and cylinder noise
Worn piston, ring and cylinder bore
Connecting rod noise
Worn rod bearing
Worn crank pin
Loose connecting rod nuts
Low oil pressure
Crankshaft noise
Low oil pressure
Worn bearing
Worn crankshaft journal
Loose bearing cap bolts
Excessive crankshaft thrust play
Valve lash in Section 6A1
Valves inspection in Section 6A1
Valve springs inspection in
Section 6A1
Valves inspection in Section 6A1
Pistons and cylinders inspection
in Section 6A1
Crank pin and connecting rod
bearing inspection in Section 6A1
Crank pin and connecting rod
bearing inspection in Section 6A1
Connecting rod installation in
Section 6A1
Previously outlined
Previously outlined
Crankshaft and bearing
inspection in Section 6A1
Crankshaft and bearing
inspection in Section 6A1
Crankshaft inspection in
Section 6A1
Crankshaft thrust play inspection
in Section 6A1
6-1-24 ENGINE GENERAL INFORMATION AND DIAGNOSIS (SFI FOR G13)
ConditionPossible CauseReferring Item
OverheatingInoperative thermostat
Poor water pump performance
Clogged or leaky radiator
Improper engine oil grade
Clogged oil filter or oil strainer
Poor oil pump performance
Faulty radiator fan control system
Dragging brakes
Slipping clutch
Blown cylinder head gasketThermostat in Section 6B
Water pump in Section 6B
Radiator in Section 6B
Engine oil and oil filter change in
Section 0B
Oil pressure check in Section 6A1
Oil pressure check in Section 6A1
Radiator fan control system in
Section 6E2
Trouble diagnosis in Section 5
Trouble diagnosis in Section 7C
Cylinder head in Section 6A1
Poor gasoline
mileageIgnition system out of order
Leaks or loose connection of high-tension cord
Faulty spark plug (improper gap, heavy deposits
and burned electrodes, etc.)
Engine and emission control system out of
order
Malfunctioning EGR valve
High idle speed
Poor performance of TP sensor, ECT sensor or
MAP sensor
Faulty EGR valve
Faulty fuel injector(s)
Faulty ECM (PCM)
Low compression
Others
Poor valve seating
Dragging brakes
Slipping clutch
Thermostat out of order
Improper tire pressure
High-tension cords in Section 6F1
Spark plugs in Section 6F1
EGR system in Section 6E2
Refer to item “Improper engine
idle speed” previously outlined
TP sensor, ECT sensor or MAP
sensor in Section 6E2
EGR system in Section 6E2
Diagnostic Flow Table B-1
Previously outlined
Valves inspection in Section 6A1
Trouble diagnosis in Section 5
Trouble diagnosis in Section 7C
Thermostat in Section 6B
Refer to Section 3F
Excessive engine
oil consumptionOil leakage
Blown cylinder head gasket
Leaky camshaft oil seals
Oil entering combustion chamber
Sticky piston ring
Worn piston and cylinder
Worn piston ring groove and ring
Improper location of piston ring gap
Worn or damaged valve stem seal
Worn valve stem
Cylinder head in Section 6A1
Camshaft in Section 6A1
Piston cleaning in Section 6A1
Pistons and cylinders inspection
in Section 6A1
Pistons inspection in Section 6A1
Pistons assembly in Section 6A1
Valves removal and installation in
Section 6A1
Valves inspection in Section 6A1
ENGINE GENERAL INFORMATION AND DIAGNOSIS (SFI FOR G13) 6-1-25
ConditionPossible CauseReferring Item
Engine hesitates
(Momentary lack of
response as
accelerator is
depressed.
Can occur at all
vehicle speeds.
Usually most severe
when first trying to
make vehicle move,
as from a stop sign.)Ignition system out of order
Spark plug faulty or plug gap out of adjustment
Leaky high-tension cord
Fuel system out of order
Fuel pressure out of specification
Engine and emission control system out of
order
Malfunctioning EGR valve
Poor performance of TP sensor, ECT sensor or
MAP sensor
Faulty fuel injector
Faulty ECM (PCM)
Engine overheating
Low compression
Spark plugs in Section 6F1
High-tension cords in Section 6F1
Diagnostic Flow Table B-3
EGR system in section 6E2
TP sensor, ECT sensor or MAP
sensor in Section 6E2
Diagnostic Flow Table B-1
Refer to “Overheating” section
Previously outlined
Surge
(Engine power
variation under
steady throttle or
cruise.
Feels like vehicle
speeds up and down
with no change in
accelerator pedal.)Ignition system out of order
Leaky or loosely connected high-tension cord
Faulty spark plug (excess carbon deposits,
improper gap, and burned electrodes, etc.)
Fuel system out of order
Variable fuel pressure
–Kinky or damaged fuel hose and lines
–Faulty fuel pump (clogged fuel filter)
Engine and emission control system out of
order
Malfunctioning EGR valve
Poor performance of MAP sensor
Faulty fuel injector
Faulty ECM (PCM)
High-tension cords in Section 6F1
Spark plugs in Section 6F1
Diagnostic Flow Table B-3
EGR system in Section 6E2
MAP sensor in Section 6E2
Diagnostic Flow Table B-1
Excessive
detonation
(Engine makes
continuously
sharp metallic
knocks that change
with throttle opening.
Sounds like pop corn
popping.)Engine overheating
Ignition system out of order
Faulty spark plug
Loose connection of high-tension cord
Fuel system out of order
Clogged fuel filter (faulty fuel pump) or fuel lines
Air inhaling from intake manifold or throttle body
gasket
Engine and emission control system out of
order
Malfunctioning EGR valve
Poor performance of ECT sensor or MAP sensor
Faulty fuel injector(s).
Faulty ECM (PCM)
Excessive combustion chamber depositsRefer to “Overheating” section
Spark plugs in Section 6F1
High-tension cords in Section 6F1
Diagnostic Flow Table B-1 or B-2
EGR system in Section 6E2
ECT sensor or MAP sensor in
Section 6E2
Diagnostic Flow Table B-1
Piston and cylinder head cleaning
in Section 6A1
ENGINE GENERAL INFORMATION AND DIAGNOSIS (SFI FOR G13) 6-1-101
1. Fuel injector
2. Delivery pipe
3. Fuel regulator
4. Fuel filter
5. Fuel pump
Special Tool
(A) Gauge (09912-58441)
(B) Hose (09912-58431)
(C) 3-way joint (09912-58490)
TABLE B-3 FUEL PRESSURE CHECK
INSPECTION
STEPACTIONYESON
11) Release fuel pressure from fuel feed line.
2) Install fuel pressure gauge.
3) Check fuel pressure by repeating ignition switch
ON and OFF.
Is fuel pressure then 270 – 310 kPa
(2.7 – 3.1 kg / cm
2, 38.4 – 44.0 psi)?
Go to Step 2.Go to Step 5.
2Is 200 kPa (2.0 kg / cm2, 28.4 psi) or higher fuel
pressure retained for 1 minute after fuel pump is
stopped at step 1?Go to Step 3.Go to Step 4.
31) Start engine and warm it up to normal operating
temperature.
2) Keep it running at specified idle speed.
Is fuel pressure then within 200 – 240 kPa
(2.0 – 2.4 kg / cm
2, 28.4 – 34.1 psi)?
Normal fuel pressure.Clogged vacuum
passage for fuel
pressure regulator or
faulty fuel pressure
regulator.
4Is there fuel leakage from fuel feed line hose, pipe or
their joint?Fuel leakage from
hose, pipe or joint.Go to Step 10.
5Was fuel pressure higher than spec. in step 1?Go to Step 6.Go to Step 7.
61) Disconnect fuel return hose from fuel pressure
regulator and connect new return hose to it.
2) Put the other end of new return hose into approved
gasoline container.
3) Operate fuel pump.
Is specified fuel pressure obtained then?Restricted fuel return
hose or pipe.Faulty fuel pressure
regulator.
6-1-102 ENGINE GENERAL INFORMATION AND DIAGNOSIS (SFI FOR G13)
1. Fuel delivery pipe
2. Fuel feed hose
3. Fuel return hose
Special Tool
(A) Gauge
(B) Hose
(C) 3-way joint
STEPACTIONYESON
7Was no fuel pressure applied in step 1?Go to Step 8.Go to Step 9.
8With fuel pump operated and fuel return hose blocked
by pinching it, is fuel pressure applied?Faulty fuel pressure
regulator.Shortage of fuel or fuel
pump or its circuit
malfunction.
91) Operate fuel pump.
2) With fuel return hose blocked by pinching it, check
fuel pressure.
Is it 450 kPa (4.5 kg / cm
2, 63.9 psi) or more?
Faulty fuel pressure
regulator.Clogged fuel filter,
restricted fuel feed
hose or pipe, Faulty
fuel pump or fuel
leakage from hose
connection in fuel
tank.
101) Disconnect fuel return hose from pressure
regulator and connect new return hose to it.
2) Insert the other end of new return hose into
approved gasoline container.
3) Check again if specified pressure is obtained.
While doing so, does fuel come out of return hose?Faulty fuel pressure
regulator.Fuel leakage from
injector, Fuel leakage
from between injector
and delivery pipe,
Faulty fuel pump
(faulty check valve in
fuel pump) or Fuel
leakage from fuel
pressure regulator
diaphragm.
Fig. for STEP 1
6C
ENGINE FUEL 6C-1
GENERAL DESCRIPTION6C-1 . . . . . . . . . . . . . .
Fuel System 6C-1. . . . . . . . . . . . . . . . . . . . . . . . . . .
Fuel Pump Assembly 6C-1. . . . . . . . . . . . . . . . . . . ON-VEHICLE SERVICE6C-2 . . . . . . . . . . . . . . . .
Fuel Lines 6C-2. . . . . . . . . . . . . . . . . . . . . . . . . . .
Fuel Tank 6C-2. . . . . . . . . . . . . . . . . . . . . . . . . . .
Fuel Pump Assembly 6C-4. . . . . . . . . . . . . . . . .
SECTION 6C
ENGINE FUEL
NOTE:
For the descriptions (items) not found in this section, refer to the same section of Service Manual men-
tioned in FOREWORD of this manual.
CONTENTS
CAUTION:
BE SURE TO USE UNLEADED FUEL ONLY. USE OF LEADED AND / OR LOW LEAD FUEL CAN RESULT
IN ENGINE DAMAGE AND REDUCE THE EFFECTIVENESS OF THE EMISSION CONTROL SYSTEM.
GENERAL DESCRIPTION
FUEL SYSTEM
The main components of the fuel system are fuel tank, fuel pump, fuel filter and fuel level gauge and it includes
three lines; fuel feed line, fuel return line and fuel vapor line.
For the details of fuel vapor flow, refer to Section 6E “ENGINE AND EMISSION CONTROL SYSTEM”.
FUEL PUMP ASSEMBLY (WITH FUEL LEVEL
GAUGE)
The fuel pump assembly consists of fuel pump and fuel level gauge.
For structure and operation of the fuel pump, refer to Section 6E.