fuel pressure MAZDA 626 1987 Repair Manual
[x] Cancel search | Manufacturer: MAZDA, Model Year: 1987, Model line: 626, Model: MAZDA 626 1987Pages: 1865, PDF Size: 94.35 MB
Page 626 of 1865
FUEL SYSTEM 4C
FUEL TANK
Removal
Caution
a) Before performing the following procedure, release the fuel pressure from the fuel sys-
tem to reduce the possibility of injury or fire. (Refer to page 4C—52.)
b)When removing the fuel tank, keep sparks, cigarettes, and open flames away from the
fuel tank.
Remove in the sequence shown in the figure.
76G04C-125
Note
Drain the fuel from the fuel tank before removing the tank.
1. Remove fuel filler cap.
2. Fuel pump connectors
3. Fuel hoses
4. Steering angle transfer shaft (4-wheel
steering)
(Refer to section 10)
5. Cross member (4-wheel steering)
6. Evaporative hoses
7. Fuel filler hose
8. Breather hose
9. Parking cable bracket
10. Fuel tank strap
11. Fuel tank
4C-65
Page 629 of 1865
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
Page 630 of 1865
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
Page 631 of 1865
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
Page 641 of 1865
4C EEC SYSTEM
EVAPORATIVE EMISSION CONTROL
(EEC)
SYSTEM
Water thermo sensor
76G04C-150
Unleaded fuel:
This system stores fuel vapor generated in the fuel tank in the canister when the engine is not running.
The fuel vapor is stored in the canister until it is drawn into the dynamic chamber and burned when
the engine is started.
Leaded fuel:
Fuel vapor generated in the fuel tank flows out to the atmosphere.
COMPONENT DESCRIPTION
Application
Component Function Remark New
model Prevtoui model
Air flow sensor Detects amount of intake air; sends signal to engine control unit
O X
Charcoal canister Stores fuel tank fumes while engine stopped
o X
Engine control unit Detects signals from input sensors and
switches; controls solenoid valves (Purge
control)
o X
Ne signal pick-up Detect crank angle at 180° intervals; sends signal to engine control unit
Installed in distributor o X
Separator Prevents fuel from flowing into charcoal canister
o o
Solenoid valve
(No.1 purge control)
Controls vacuum to solenoid valve (No.2
purge control) and vacuum switch valve
0 X
Solenoid valve (No.2 Purge control)
Controls vacuum to vacuum switch valve o X
Three-way check valve Controls pressure in fuel tank o X
Two-way check valve Controls pressure in fuel tank X o
Vacuum switch valve Regulates evaporative fumes from canis-ter to intake manifold
o X
Water thermo sensor Detects coolant temperature; sends signal to engine control unit
0 X
76G04C-151
4C-80
Page 645 of 1865
4C EEC SYSTEM
Solenoid Valve
1. Remove the solenoid valve.
76G04C-159
2. Connect vacuum hoses to the valve as shown in
the figure.
3. Blow air through the valve from hose A and check
that air comes out of the valve air filter.
4. Apply 12V and ground the solenoid valve with jum-
per wires.
5. Blow air through the valve from hose A and check
that the air comes out of port B.
6. Replace, if necessary.
86U04A-151
Two-way check valve
Inspection
1. Remove the two-way check valve.
76G04C-160
4C-84
Connect a pressure gauge to the passage that nor-
mally is connected to the fuel tank.
Blow through the valve from port A. Verify that the
valve opens at 2.94 kPa (0.03 kg/cm2,0.43 psi).
Remove the pressure gauge and connect
it
to the
passage to atmosphere.
Blow through the valve from port B. Verify that the
valve opens at 0.98 kPa (0.01 kg/cm2,0.14 psi).
Page 652 of 1865
CONTROL SYSTEM 4C
CONTROL SYSTEM
Throttle sensor
Solenoid Solenoid Idle valve valve switch (VIC) (PRC)
Solenoid
valve
control)*
Solenoid valve
'(No.1 purge control)*1
E/L control unit
Engine control unit
Control relay
Injector
Knock sensor* -
Water thermo
switch*1
"1...Unleaded fuel
*2...Leaded fuel
Oxygen Distributor Water thermo sensor*1 sensor
Clutch switch
Oxygen sensor
relay*1
Solenoid valve
(EGR)*1
/ Solenoid valve 7 (ISC)
Air flow sensor
Neutral switch
76G04C-166
The control system consists of the input devices and the engine control unit. The control unit controls
the fuel injection amount (EGI), fuel injection pressure, bypass air amount, ignition timing, switch moni-
tor function, and fail-safe function.
4C-91
Page 653 of 1865
4C CONTROL SYSTEM
RELATIONSHIP CHART
Output Devices
and
Input Devices (Unleaded fuel)
IGNITION SWITCH
(ON POSION) X X X X X O X X X X X X X X O
TEST CONNECTOR X X X O X X X X X X X X X O X
ELECTRICAL LOAD CONTROL UNIT X X X o X X X X X X X X X X X
P/S PRESSURE SWITCH X X X o X X X X X X X X X X X
A/C SWITCH X X X o X X X X X X X X O X X
IGNITION SWITCH
(STA POSITION) O O X o O X X X X O X X X O X
NEUTRAL
AND
CLUTCH SWITCH O X X o X X X X X X X X X X X
OXYGEN SENSOR o X X X X X X X X X X X X X X
WATER THERMO
SWITCH (RADIATOR) o X X X X X X X o X X X X X X
INTAKE
AIR
THERMO SENSOR X X X X X X X X X O X X X X X
WATER
THERMO SENSOR o X X o X X o o O O X X X O o
IDLE SWITCH o X X o X X X X X o X X X O X
THROTTLE SENSOR o X X X X X X X O X X X X o X
AIR FLOW SENSOR o X X X X X X o X X X X X o O
Ne SIGNAL o o X O o X X O O O o o X o O
G SIGNAL X O X X X X X X X X X X X X X
\
INPUT
DEVICE
OUTPUT
DEVICE
FUEL
INJECTION
AMOUNT FUEL
INJECTION
TIMING
AIR
VALVE
ISC
VALVE
FUEL
PUMP
CONTROL
MAIN
POWER
CONTROL
SOLENOID
VALVE
(No.1
PURGE)
SOLENOID
VALVE
(No.2
PURGE)
SOLENOID
VALVE
(EGR)
SOLENOID
VALVE
(PRESSURE
REGULATOR
CONTROL)
SOLENOID
VALVE
(VARIABLE
INERTIA
CONTROL)
OXYGEN
SENSOR
RELAY
I A/C
RELAY
IGNITER
AIR
FLOW
SENSOR
(BURN-OFF)
\
INPUT
DEVICE
OUTPUT
DEVICE
INJECTOR
BAC
VALVE
CONTROL
RELAY
SOLENOID
VALVE
(No.1
PURGE)
SOLENOID
VALVE
(No.2
PURGE)
SOLENOID
VALVE
(EGR)
SOLENOID
VALVE
(PRESSURE
REGULATOR
CONTROL)
SOLENOID
VALVE
(VARIABLE
INERTIA
CONTROL)
OXYGEN
SENSOR
RELAY
I A/C
RELAY
IGNITER
AIR
FLOW
SENSOR
(BURN-OFF)
76G04C-167
4C—92
Page 654 of 1865
CONTROL SYSTEM 4C
Output Devices and In put Devices (Leaded fuel)
IGNITION SWITCH
(ON POSITION) X X X X X O X X X X O
TEST CONNECTOR X X X O X X X X X O X
KNOCK SENSOR X X X X X X X X X o X
ELECTRICAL LOAD
CONTROL UNIT X X X O X X X X X X X
P/S PRESSURE SWITCH X X X o X X X X X X X
A/C SWITCH X X X o X X X X O X X
IGNITION SWITCH (STA POSITION) O O X o O X O X X O X
NEUTRAL AND
CLUTCH SWITCH O X X o X X X X X X X
INTAKE AIR THERMO SENSOR X X X X X X O X X X X
WATER THERMO SENSOR O X X o X X O X X O o
IDLE SWITCH o X X o X X o X X O X
VARIABLE RESISTOR (IN AIR FLOW SENSOR) o X X X X X X X X X X
AIR FLOW SENSOR o X X X X X X X X O O
Ne SIGNAL o o X O o X O o X o O
G SIGNAL X O X X X X X X X X X
INPUT
DEVICE
OUTPUT
DEVICE
FUEL
INJECTION
AMOUNT
FUEL
INJECTION
TIMING
AIR
VALVE
ISC
VALVE
FUEL
PUMP
CONTROL
MAIN
POWER
CONTROL
SOLENOID
VALVE
(PRESSURE
REGULATOR
CONTROL)
SOLENOID
VALVE
(VARIABLE
INERTIA
CONTROL)
A/C
RELAY
IGNITER
AIR
FLOW
SENSOR
(BURN-OFF)
INPUT
DEVICE
OUTPUT
DEVICE
INJECTOR
BAC
VALVE
CONTROL
RELAY
SOLENOID
VALVE
(PRESSURE
REGULATOR
CONTROL)
SOLENOID
VALVE
(VARIABLE
INERTIA
CONTROL)
A/C
RELAY
IGNITER
AIR
FLOW
SENSOR
(BURN-OFF)
76G04C-168
4C—93
Page 655 of 1865
4C CONTROL SYSTEM
Output Devices
and
Engine Conditions (Unleaded fuel)
REMARK
*
Above
7,000
rpm:
fuel
cut
'Coolant
temp.:
below
50°C
(122°F)
41 Coolant
temp:
below
70°C
(158°F)
*2 Engine
speed
above
1,700
rpm
*3 Engine
speed:
1,500—3,500
rpm
*
During
hot
start
only
*
Engine
speed:
above
5,200
rpm
'Engine
speed:
above
3,000
rpm
'Delays
0.5
second
IGN:
ON
(ENGINE
NOT RUNNING)
No
injection
No bypass OFF
(main
fuel
pump
not
operated)
OFF
OFF
z
1
IDLE
(THROTTLE
VALVE
FULLY CLOSED)
Rich
and
i
lean
Sequential
(once
per
two
revolutions)
OFF
o en C3 UJ
z
"After
start-
ing:
ON
(Vacuum
cut) OFF
o
DECELE-
RATION
'Fuel
cut
L
Small
amount
of
bypass
air
N (1st
stage
operate:
o
o Ho 3 O CO CD > CO >
>; CO
CO c o
c o o
HEAVY
LOAD
•ST c
Closed
Small
amount
of
bypass
air
-co-CD CO
N (1st
stage
operate:
In CD 2? 03 a. o CD o> CO to "O c
*3 OFF (EGR)
o Ho 3 O CO CD > CO >
03 k-o CO c 03 CO z o *
CD c O) c 03 c o
c o o a 3
ACCELE-
RATION
Rich
o •*—• 3 o > CD
O
Small
amount
of
bypass
air
03 Q. O Q. E 3
ON
O
In CD 2? 03 a. o CD o> CO to "O c
ON
(EGR cut)
:F (Vacuum
to
pressure
regulatt
03 3 -C CO o
c 03 CS3 > X o o
z o * CO •o c CD Q. CD T3
C CO CD o "O 3= O c: 3 CO
LL LL o
MEDIUM
LOAD
WARM
Rich
and lean
|
Q. CD O
CD D
C CO E
CVJ.
z o fS *
*3 OFF (EGR)
:F (Vacuum
to
pressure
regulatt
E 3 3
c 03 i t 3 G, LL LL
T3 CD O c CO > "O <
C CO CD o "O 3= O c: 3 CO
LL LL o
MEDIUM
LOAD
COLD
ro
c CD 3 cr
z O "a CD a? CD CL o
F (2nd
stage
not
operated)
:F (Vacuum
to
pressure
regulatt
z o * O «
WARMING
UP
(DURING
IDLE)
Rich
CD CO c CD Q-O
o
c 3 CO O CO E CO
o c
stage
not
operated)
tr O UJ
z o
O
LL z
Fixed
at
BTDC
12°
CRANKING
(COLD
ENGINE)
1
group
(twice
per
revolution)
CO
«
CD urn i CO
CO
LL LL O
LL O * « o o
LL LL o
Fixed
at
BTDC
6°
z o
SOLENOID
VALVE
(PRESSURE
REGU-
LATOR
CONTROL)
CC
o z o o iii z
o z 111
OUTPUT
DEVICE
FUEL
INJECTION
AMOUNT FUEL
INJECTION
TIMING
AIR
VALVE
'
ISC
VALVE
FUEL
PUMP
CONTROL
MAIN
POWER
CONTROL
SOLENOID
VALVE
(No.1
PURGE)
SOLENOID
VALVE
(NO.2
PURGE)
SOLENOID
VALVE
(EGR)
SOLENOID
VALVE
(PRESSURE
REGU-
LATOR
CONTROL)
SOLENOID
VALVE
(VARIABLE
INE
TIA
CONTROL)
> <
Ul oc oc o
£T u. O 1 z oc 3 m
oc o
OUTPUT
DEVICE
INJECTOR
BAC
VALVE
CONTROL
RELAY
SOLENOID
VALVE
(No.1
PURGE)
SOLENOID
VALVE
(NO.2
PURGE)
SOLENOID
VALVE
(EGR)
SOLENOID
VALVE
(PRESSURE
REGU-
LATOR
CONTROL)
SOLENOID
VALVE
(VARIABLE
INE
TIA
CONTROL)
tn z Ul (0 z Ul o >-X o
A/C
RELAY
IGNITER
z Ul (O
=5 o
IL oc <
76G04C-169
4C—94