engine MAZDA 626 1987 Workshop Manual

FUEL SYSTEM 4C
Pulsation damper
76G04C-100
Intake mainfold
3. Turn the ignition switch ON for 10 seconds, and
check the feeding capacity with graduated
cylinder.
Feeding capacity:
Minimum 220 cc (13.4 cu in)/10 sec.
4. If not within specification, check the fuel filter, fuel
lines and fuel pump.
5. Turn the ignition switch OFF and disconnect the
jumper wire.
PULSATION DAMPER
1. Run the engine at idle.
2. Place a finger on the screw of the pulsation damper
head.
3. Check that pulsation is felt.
86U04A-083

Injector
INJECTOR
On-vehicle Inspection
1. Warm up the engine and run it at idle.
2. Listen for operational sound of the injector with a
screwdriver or a sound scope.
76G04C-101
3. Ground the test connector (Green, 1-pin).
76G04C-102
4C-57

4C FUEL SYSTEM
76G04C-103
76G04C-104
76G04C-105
- s A Test connector I \ (Yellow)
4. Disconnect the connector from each injector
respectively.
5. Check that the engine speed decreases about
100—200 rpm each time.
6. If not correct, check the following:
No operating sound and no speed drop
Check injector wiring harness
No speed drop only
Injector resistance
Injection volume of injector
Inspection
Perform the following inspections.
Resistance
1. Remove the injectors from the engine. (Refer to
page 4C—61.)
2. Check the resistance of each injector with an
ohmmeter.
3. If not correct, replace the injector.
Resistance: 12—16 Q
Fuel leakage test and volume test
1. Remove the injectors and delivery pipe. (Refer to
pages 4C—61 and 63.)
2. Affix the injectors to the delivery pipe with wire.
Caution
Affix the injectors firmly so that no movement
is possible.
Warning
Be extremely careful when working with fuel.
Always work away from sparks or open
flames.
3. Connect the terminals of the test connector (Yel-
low) with a jumper wire. Turn the ignition switch ON.
4. Check that no fuel leaks from the injector nozzles.
Note
After 1 minute, a drop of fuel from the injec-
tor is acceptable.
76G04C-106
4C—58

FUEL SYSTEM 4C
76G04C-112
86U04B-083
76G04C-113
Transfer Pump
1. Remove the fuel tank. (Refer to page 4C—65.)
2. Disconnect the fuel hoses from the transfer pump.
3. Remove the transfer pump.
4. Install in the reverse order of removal.
Injector
1. Remove the engine hanger.
2. Remove the wiring harness bracket.
3. Disconnect the PCV valve and hose from the dy-
namic chamber.
76G04C-114
4C-61

4C FUEL SYSTEM
4. Disconnect the main fuel hose from the delivery
pipe assembly.
5. Disconnect the fuel return hose from the fuel re-
turn pipe.
6. Remove fuel return pipe mounting bolt.
76G04C-115
7. Remove the delivery pipe assembly mounting bolts
and insulators.
76G04C-116
Remove the grommets, injectors, and insulators.
Install in the reverse order of removal, referring to
the installation note.
Tightening torque:
Delivery pipe, dynamic chamber, and en-
gine hanger
19—25 N m (1.9—2.6 m-kg, 14—19 ft-lb)
76G04C-117
O-ring Injector / Correct
v L
Grommet Delivery pipe
Wrong
/
Dc^Li Wrong
Installation note
Injector
1. Use new O-rings.
2. Apply a small amount of engine oil to the O-rings
when installing.
86U04A-108
4C-62

4C FUEL SYSTEM
^ Pulsation
damper
76G04C-121
Pulsation damper
—
Delivery pipe
76G04C-122
Fuel hose
,Fuel pump
-Intank filter
76G04C-123
Insulator
f f r—
/ 0 DM

•
II r
O - ring
Grommet
Manifold
Delivery pipe
Pressure Regulator
1. Remove the engine hanger.
2. Disconnect the vacuum hose and fuel return hose.
3. Remove the pressure regulator.
4. Install in the reverse order of removal.
Tightening torque:
8—11 Nm (0.8—1.1 m-kg, 69—95 in-lb)
Pulsation Damper
1. Remove the delivery pipe assembly. (Refer to page
4C-63.)
2. Remove the pulsation damper.
3. Install in the reverse order of removal.
Tightening torque:
25—34 N m (2.5—3.5 m-kg, 18—25 ft-lb)
Fuel Filter
Low pressure side (In-tank filter)
Refer to page 4C—60.
76G04C-124
High pressure side
The fuel filter must be replaced at the intervals out-
lined in the maintenance schedule.
Warning
Always work away from sparks or open
flames.
1. Disconnect the fuel hoses from the fuel filter.
2. Remove the fuel filter and the bracket.
3. Install a new filter and the bracket.
4. Connect the fuel hoses.
Note
When installing the filter, push the fuel hoses
fully onto the fuel filter and secure them with
spring clamps.
4C-64

4C PRC SYSTEM
PRESSURE REGULATOR CONTROL
(PRC)
SYSTEM
Distributor (Ne signal)
I Fuel
(To fuel tank)
76G04C-128
To prevent percolation of the fuel during idle after the engine is restarted, vacuum is cut to the pres-
sure regulator, increasing the fuel pressure.
Specified time: Approx. 120 sec.
Operating condition: Coolant temperature — above 70°C (158°F)
Intake air temperature — above 30°C (86°F)....Unleaded fuel
above 50°C (122°F)....Leaded fuel
4C-68

PRC SYSTEM 4C
COMPONENT DESCRIPTION
Component Function Remark
Engine control unit Detects signals from input sensors and switches; con-trols solenoid valve (Pressure regulator control)
Ignition switch
(ST position)
Sends engine cranking signal to engine control unit
Intake air thermo sensor Detects intake air temperature; sends signal to engine control unit
Ne signal pick-up Detects crank angle at 180° intervals; sends signal to engine control unit Installed in distributor
Pressure regulator Adjusts fuel pressure supplied to injectors
Solenoid valve (Pres-
sure regulator control)
Controls vacuum to pressure regulator Cuts vacuum when hot
Water thermo sensor Detects coolant temperature; sends signal to engine control unit
Idle switch Detects when throttle valve closed; sends signal to engine control unit ON at idle
76G04C-129
TROUBLESHOOTING
Check the condition of the wiring harness and connections before checking the sensors or switches.
Note
Make the system inspection first. If no problem is found, continue with inspection of the
next system of the Troubleshooting Guide. (Refer to pages 4C—10 and 11.)
Possible
\ cause
\ Page
Solenoid valve (Pres-sure regula-tor control)
Water thermo
sensor
Intake air
thermo
sensor
Engine con-trol unit terminal
System inspection Solenoid valve (Pres-sure regula-tor control) 2K
Symplon 4C—70 4C—107 4C-110 4C—98 4C—70
Engine stalls or runs rough after hot starting 2 3 4 5 1
76G04C-130
4C-69

4C PRC SYSTEM
System Inspection
1. Connect the SST to the engine. (Refer to page
4C-53.)
2. Start the engine.
76G04C-131
Hi?
Jpll ssil
Water thermo sensor ^^^Tta^e air thermo sensor
76G04C-132
Operating time Fuel line pressure kPa (kg/cm2, psi)
After starting: for 120 sec. 235-275 (2.4-2.8, 34-40)
After 120 sec. 186-226 (1.9-2.3, 27-33)
3. Warm up the engine to normal operating temper-
ature and stop the engine.
Warning
Be careful when disconnecting the water ther-
mo sensor connector because the surround-
ing area is very hot.
4. Disconnect the water thermo sensor connector.
Connect a resistor (200 fl) to the sensor connector.
5. Heat the intake air thermo sensor to above specifi-
cation.
Specification: 30°C (86°F)....unleaded fuel
50°C (122°F)....leaded fuel
6. Restart the engine.
7. Check the fuel line pressure and operating times
as shown in the chart.
76G04C-133
Solenoid Valve (Pressure Regulator Control)
Inspection
1. Disconnect the vacuum hose from the vacuum
pipe.
2. Blow through the solenoid valve from vacuum hose
A.
3. Check that air flows from port B.
76G04C-134
4C—70

4C DECELERATION CONTROL SYSTEM
DECELERATION CONTROL SYSTEM
Distributor
(Ne signal)
Idle switch
QSO-Water thermo sensor
=5
A/C switch
Engine control unit
Detection of
fuel cut
condition Determi-
nation of
fuel cut
speed
* *
1
T
No.3

I
No.4
No.2
The fuel cut system is provided as a deceleration control system.
This system is to improve fuel consumption.
86U04A-121
4C—72

DECELERATION CONTROL SYSTEM 4C
COMPONENT DESCRIPTION
Component Function Remarks
Engine control unit Detects signals from input sensors and switches; cuts fuel injection
Idle switch Detects when throttle valve fully closed; sends signal to engine control unit ON at idle
Ne signal pick-up Detects crank angle at 180° intervals; sends signal to engine control unit Installed in distributor
Water thermo sensor Detects coolant temperature; sends signal to engine control unit
76G04C-135
TROUBLESHOOTING
Check the condition of the wiring harness and connectors before checking the sensor or switches.
Note
Make the system inspection first. If no problem is found, continue with inspection of the
next system of the Troubleshooting Guide. (Refer to page 4C—10 and 11.)
Possible cause Water thermo sensor System inspection
Page 4C—107 4C—74
Checking order 2 1
76G04C-136
4C-73