1990 MAZDA 232 fuel

F2 FUEL SYSTEM
FUEL VAPOR VALVE
FUEL VAPOR VALVE
93GOF2-722
The fuel vapor valve is installed in the fuel tank to allow fuel vapors within the tank to escape to the charcoal
canister.
The fuel vapor valve contains a shut-off valve to prevent raw fuel from escaping during hard cornering
01
at other times when there is significant fuel slosh.
FUEL PUMP CONTROL SYSTEM [BP TURBO]
Outline
l The fuel pump control system supplies electric power to the fuel pump at ail times while the engine is
running. The fuel pump can thus operate even though the fuel pump switch in the airflow meter OFF.
rhe fuel pump switch may open (switch OFF) on deceleration due to back-flow of air from the turbocharger.]
l To improve fuel pump longevity, the fuel pump is controlled by the engine control unit (ECU). (Refer to
next page.)
MAIN RELAY (FUEL 1NJ RELAY)
I I FUEL PUMP
RESISTOR/RELAY ECU
I
ON
P CIRCUIT OPENING
I--
DIAGNOSIS
CONNECTOR
TERMINAL F/P CPU
F2-16

FUEL SYSTEM F2
Two-stage WeI pump operation
Engine running (Except heavy load or cranking)
The ECU 1 I circuit is ON, opening the contact plate in the fuel pump resistor/relay. Current from the circuit
opening relay to the fuel pump flows through the resistor in the fuel pump resistor/relay, and the voltage
to the fuel pump is reduced to approx. WV, causing the fuel pump to operate at a reduced speed to im-
move fuel pump longevity.
MAIN RELAY
Engine under heavy load or cranking
The ECU 1 I circuit is OFF and the contact plate in the fuel pump resistor/relay is closed. Unreduced battery
current flows to the fuel pump through the contact plate, causing the fuel pump speed and output to be
increased to meet the demands of the engine.
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93GW2-725
FZ-17

F2 FUEL SYSTEM
93GOF2-726
FUEL PUMP RESISTOR/RELAY [BP TURBO]
The fuel pump resistorlretay supplies battery voltage to the
fuel pump when the ECU 11 circuit is OFF, and approx. 1 OV
when the ECU 11 circuit is ON. It is mounted on the firewall.
TRANSFER PUMP CONTROL
Outline
The fuel tank is buitt with separate right and left sections to accommodate the. installation of the propeller
shaft. As fuel is puited from the right side of the tank, the transfer pump pumps the fuel from the left to the
right (fuel pumb) side to balance the fuel level.
FUEL IN LEFT TANK
I
FUEL PUMP CONTROL. UNIT
/ TRANSFER PUMP
TRANSFER PUMP SWITCH: OFF
NO FUEL IN LEFT
TANK
FUEL PUMP CONTROL UNIT / TRiNSFER PUMP
TRANSFER PUMP SWITCH: UN
93GOF2-727
Operation 1. Whenever the ignition switch is ON and fuel is in the left (transfer pump)
side of the fuel tank the fuel pump switch is open, the transfer pump circuit in the fuel pump control unit is
closed, and the transfer pump
operates.
2. When the fuel in the left side of the tank drips betow a specified point, the fuel pump switch is grounded
and the transfer pump stops operation.
3. To prevent the transfer pump from
being turned ON and OFF repeatedly, possibly shorting the life of the
pump, when the vehicle is driven on a rough
road and the fuel level is low, there is a ten-second delay
circuit in the control unit to delay the turning ON and OFF the pump.
f2--I 8

FUELSYSTEM F2
Transfer Pump Switch
- -
93GOF2-726
The
fuel pump switch is a float-type ON/OFF switch used to operate the transfer pump. It is part of the fuel
gauge sender unit. ^_

F2 CONTROL SYSTEM
CONTROL
SYSTEM
STRUCTURAL VIEW
OXL STOPLIGHT SWITCH CLUTCH SWITCH
INJECTOR
P/S PRESSURE
SWITCH
‘GEN SE877
DtSTRIBUTOR
/ PUMP
CONTROL UNll
CONTROL UNIT
CONNECTOR
P REStSTORlRELAY
FUEL tNJ RELAY (MAIN RELAY)
AIRFLOW METER
SOLENOID VALVE
I NEUTRAL SWITCH
(PRESSURE REGULATOR)
WATER THERMOSENSOR
93GOf2.729

F2 CONTROL SYSTEM
KNOCK CONTROL SYSTEM [BP TURBO]
This svstem retards the ignition timina when enaine knocking occurs because of usage of low octane fuel, etc.
1NTAKE
MANIFO
KNOCK SENSOR
(INSTALLED BETWEEN No.2 AND
No.3 CYLINDER)
IGNITER
KNOCK iX?NTROL
UNIT
Operation
When the engine vibrates, the knock sensor generates a slight voltage signal that is the sent to the knock
control unit. The knock control unit determines whether the signal is a knocking signal. If it is a knocking
signal, the ignition spark is retarded according to the intensity of the knock to a maximum of 4O.
Inhibition of spark retardation
In order to improve drivability and fuel economy, the ECU inhibits the above spark retardation when the
‘engine load Ls light, the coolant temperature is below O°C (32OF), the engine is cranking during engine test
conditions.
Note
l The knock ~ensur and knock control unit cannot be inspected individually.
When a matfunction code number 05 is indicated, replace the knock controt unit or sensor
only after inspecting the related wiring and connectors.
F2-22

CONTROL SYSTEM F2
t OXYGEN SENSOR [BP TURBO]
I
CERAMlC HEATER
93GOF2-733
Because the temperature of the exhaust gas is inherently low in turbocharged engines, the BP Turbo model
uses a rapid heating ceramic heater to detect the air/fuel ratio,
PRESSURE REGULATOR CONTROL SYSTEM [BP TURBO]
PRESSURE
REGULATOR
I SOLENOID VALVE
(PRESSURE REGULATOR CONTROL)
FUEL
+ (FROM
DELIVERY PIPE1
II
FUEL INJ I
RELAY
(MAIN REU\Y)
I
II Ir
-__. _ - -’ VACUUM
CT0 DYNAMIC
Ill
CHAMBER)
BATTERY -
c
FUEL
(TO FUEL TANK)
nme*rn -.-a
To prevent percolation of the fuel during hot restart idle, vacuum to the pressure regulator k cut for 180
sec., and the fuel injection pressure is increased to slightly more than 284 kPa (2.90 kg/cm’, 41.2 psi).
Operating condition
l Coolant temperature: Above 90°C (194OF)
l Intake air temperature: Above 58OC (136OF)
g No-load condition
FZ-23

SUPPLEMENTAL SERVICE INFORMATION F2
SUPPLEMENTAL SERVICE INFORMATION
The following points in this section are changed in comparison to the Mazda 323 Workshop Manual
[I 203-I U-89F (Europe) or 120410-89F {Australia)].
intake air system components [BP Turbo]
l Removalllnspectionll nstaltation
WASTEGATE [BP Turbo]
l Inspection
WASTEGATE SULENOlD VALVE [BP Turbo]
l Inspection
Turbocharger [BP Turbo]
l Inspection
l Removalllnstaltation
Air bypass valve [BP Turbo]
l Removal/hstallation
l 1 nspection
lntetcoolet [BP Turbo]
l RemovaMnspection/tnstaltation
Fuel tank
l Removal ! Inspection I Installation
Fuel pump control unit [BP Tubto]/4x4 control unit [BP SOHC]
l 1 nspection
l Replacement
Transfer pump switch
l Inspection
l Replacement
Transfer pump
l Inspection
l Replacement
Fuel pump resistor/relay
l System operation
l Inspection
injector [8P Turbo]
l Volume test
Exhaust system components
l Removal / 1 nspection / Installation
Engine control unit (ECU) [BP Turbo]
l Terminal voftage
Oxygen sensor [BP Turbo]
l Inspection
l Replacement
Knock sensor [BP Turbo]
l Replacement 93GOFZ736
F2-25