1987 MAZDA 626 fuel pump

4B INTAKE AIR SYSTEM
INTAKE AIR SYSTEM
76G04B-036
This system controls the air required by the engine for operation. The system consists of the air duct,
air cleaner, air flow meter, throttle body, dynamic chamber, and intake manifold.
COMPONENT DESCRIPTIONS
Component Function Remarks
Air cleaner
Filters
air
into throttle body

Air flow meter
Detects amount
of
intake air;
sends signal
to
engine control unit Intake
air
thermo sensor and fuel pump
switch are integrated

Throttle body
Controls intake
air
quantity Integrated throttle sensor and idle switch

76G04B-037
4B—30

4B FUEL SYSTEM
FUEL SYSTEM
76G04B-057
This system supplies the fuel necessary for combustion at a constant pressure to the injectors. Fuel
is metered and injected into the intake manifold according to the injection control signals from the en-
gine control unit. It consists of the fuel pump, fuel filters, delivery pipe, pulsation damper, pressure
regulator, injectors, fuel pump switch (incorporated in the air flow meter), and the circuit opening relay.
The fuel pump is mounted in the fuel tank to minimize the operating noise of the fuel pump. The injec-
tors are directly supplied with battery voltage through the main relay.
4B—42

FUEL SYSTEM 4B
COMPONENT DESCRIPTIONS
Component Function Remarks
Air flow meter
Detects amount
of
intake
air;

sends signal
to
engine control unit Intake
air
thermo sensor and fuel pump
switch
are
integrated

Atmospheric pressure sensor
Detects atmospheric pressure; sends sig-nal
to
engine control unit

Circuit opening relay
Voltage
for
fuel pump while engine running

Clutch switch
Detects in-gear condition; sends signal
to
engine control unit Switch
ON
when clutch pedal released

Engine control unit
Detects signals from input sensors and switches; controls injector operation

Fuel filter
Filters particles from fuel

Fuel pump
Provides fuel
to
injectors • Operates while engine running
• Installed
in
fuel tank

Idle switch
Detects when throttle valve fully closed;
sends signal
to
engine control unit
Installed
in
throttle sensor

Ignition coil (-) terminal
Detects engine speed; sends signal
to
engine control unit

Ignition switch (ST position)
Sends engine cranking signal
to
engine control unit

Inhibitor switch
Detects in-gear condition; sends signal
to
engine control unit
Switch
ON in "N" or "P"
range

Injector
Injects fuel into intake port • Controlled
by
signals from engine control unit • High-ohmic injector

Intake air thermo sensor
Detects intake
air
temperature;
sends signal
to
engine control unit Installed
in air
flow meter

Main relay
Supplies electric current
to
injectors and engine control unit

Neutral switch
Detects in-gear condition; sends signal
to
engine control unit
Switch
ON
in-gear

Oxygen sensor
Detects Oxygen concentration; sends sig-nal
to
engine control unit
Zirconia ceramic and platinum coating

Pressure regulator
Adjusts fuel pressure supplied
to
injectors

Pulsation damper
Absorbs fuel pulsation

Throttle sensor
Detects throttle valve opening angle; sends signal
to
engine control unit
Integrated idle switch

Water thermo sensor
Detects coolant temperature;
sends signal
to
engine control unit

Water thermo switch
Detects radiator coolant temperature; sends signal
to
engine control unit ON: above 17°C (63°F)

76G04B-058
4B—43

FUEL SYSTEM 4B
Pressure .
regulator ^^ \ To multi-pressure tester
How to Connect Multi-Pressure Tester
Warning
Before connecting the SST, release the fuel
pressure from the fuel system to reduce the
possibility of injury or fire. (Refer to page
4B—45.)
1. Disconnect the negative battery terminal.
2. Disconnect the fuel main hose from the fuel filter.
3. Connect the SST between the fuel main hose and
fuel pump with the adapter.
Caution
Do not reverse the adapter connection.
4. Disconnect the vacuum hose from the pressure
regulator control solenoid valve. Connect the SST
vacuum hose with a three-way joint.
5. Connect the negative battery terminal.
6. Connect the SST to the battery.
86U04A-071
v *
- i\zLTest connector (Yellow)
7. Connect the terminals of the test connector (Yel-
low) with a jumper wire. Turn the ignition switch
ON to operate the fuel pump.
8. Check for fuel leaks.
Caution
After checking for fuel leakage, turn the igni-
tion switch OFF and disconnect the jumper
wire from the test connector.
86U04A-072
4B—47

4B FUEL SYSTEM
76G04B-061
I i. i { 1 t' i 1 I • i i 1 1 "1 —r
1 . . • , 1 ,
EDO 250
86U04A-074
w Test connector
(Yellow)
86U04A-075
Lever
To fuel pump To pulsation damper
FUEL PRESSURE
Note
a) When inspecting fuel pressure, use the
SST. (Refer to page 4B—47).
b)Warm up the engine to normal operating
temperature.
Injection Pressure
1. Set the lever on the adapter as shown in the figure.
2. Run the engine and measure the injection pres-
sure at various speeds.
Injection pressure: Approx. 235—275 kPa
(2.4—2.8 kg/cm2, 34—40 psi)
3. If not within specification, check the fuel pump pres-
sure and fuel line pressure.
Fuel Pump Pressure
1. Connect the terminals of the test connector (Yel-
low) with a jumper wire.
2. Turn the ignition switch ON to operate the fuel
pump.
3. Set the lever on the adapter as shown in the figure.
4. Check the fuel pump pressure.
Fuel pump pressure: 441—588 kPa
(4.5—6.0 kg/cm2, 64—85 psi)
5. If the fuel pump pressure is not within specifica-
tion, check the following;
No pressure
• Fuel pump operation (Refer to page
4B—49.)
Low pressure
• Fuel pump feeding capacity (Refer to
page 4B—50.)
High pressure
• Replace the fuel pump
6. After checking the fuel pump pressure, disconnect
the jumper wire from the test connector.
76G04B-062
4B—48

FUEL SYSTEM 4B
76G04B-126
86U04A-078
V^AN.
- Test connector
(Yellow)
76G04B-063
Fuel Line Pressure
1. Start the engine and run it at idle.
2. Set the lever on the adapter as shown in the figure.
3. Check the fuel line pressure.
Fuel line pressure: Approx. 186—226 kPa
(1.9—2.3 kg/cm2, 27—33 psi)
4. If not within specification, check the vacuum hose.
5. Disconnect the vacuum hose from pressure regu-
lator, and place a finger over the end of the hose.
6. Check the fuel line pressure.
Fuel line pressure: 235—275 kPa
(2.4—2.8 kg/cm2, 34—40 psi)
7. If not within specification, replace the pressure
regulator.
8. Connect the vacuum hose to pressure regulator.
FUEL PUMP
Operation Test
1. Connect a jumper wire to the test connector
(Yellow).
2. Remove the fuel filler cap.
3. Turn the ignition switch ON.
4. Listen for operational sound of the fuel pump at
the filler inlet.
5. Install the fuel filler cap.
6. If no sound is heard, check the voltage at the fuel
pump connector (WY wire and a ground).
Voltage: 12V
7. If the voltage is normal, replace the fuel pump.
8. If not correct, check the circuit opening relay (Re-
fer to page 4B—86) and its circuits.
9. Disconnect the jumper wire.
76G04B-064
4B—49

4B FUEL SYSTEM
v - \\N . Test connector
VW^^^^^^AX (Yellow)
76G04B-070
4. Connect the fuel return hose and vacuum hose to
the pressure regulator.
5. Connect the terminals of the fuel pump test con-
nector with a jumper wire. Turn the ignition switch
ON.
6. Check that no fuel leaks from the injector nozzles.
Note
After 1 minute a drop of fuel from the injec-
tor is acceptable.
7. Connect the SST to the battery and injector.
8. Check the injection volume with a graduated con-
tainer.
Injection volume:
Approx. 38—53 cc (2.3—3.2 cu in) /15 sec.
Caution
When using the SST, make sure of the SST
number and use correct one.
9. If not correct, replace the injectors.
76G04B-071
4B-52

FUEL SYSTEM 4B
REPLACEMENT
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 4B—45).
b)When servicing the fuel system, keep
sparks, cigarettes, and open flames away
from the fuel.
76G04B-077
86U04A-101
M Fuel pump
Fuel filter
Bracket
86U04A-102
Fuel Pump
1. Remove the rear seat and disconnect the fuel
pump connector.
2. Remove the service hole cover.
3. Disconnect the fuel hoses.
4. Remove the fuel pump and fuel tank gauge as-
sembly.
5. Replace the fuel pump.
Caution
Secure the fuel pump terminals and fuel hoses
securely.
6. Install in the reverse order of removal.
4B—57