HB. Checking The Fuel Pump
HB. CHECKING THE FUEL PUMP (FP)
HB1
Checking The Power Supply At The Central Electrical Module
-Ignition off.
-Remove fuse from battery (in engine compartment (-90) or no.6 (91-)).
Check that the fuse is intact.
Connect a voltmeter between the left-hand terminal on the fuse box from the battery in the engine compartment (-90) or the right-hand terminal on fuse no.6 (91-) and GND.
The voltmeter should read battery voltage.
If the reading is incorrect
The fault lies before the fuse.
-Check the wiring between the fuse and the battery.
If the reading is OK
-Check the power supply to the FP HB2.
HB2
Checking The Power Supply To The Fuel Pump (FP)
-Remove fuse 4 and check that it is intact.
Connect a voltmeter between the right-hand terminal of fuse 4 and GND.
-Operate the starter motor.
The voltmeter should read 9.5-11 V.
If this value Is OK
-Check the FP resistance HB5.
If the reading Is 0 V.
-Check the voltage to the relay board HB3.
HB3
Checking The Voltage To The Relay Board
Remove the sound proof board on the left-hand side.
-Ignition on.
Connect a voltmeter between terminals 3 and 4 on the back of the relay board.
The voltmeter should read battery voltage.
If this value is OK
-Check the control signal HB4.
If the reading is Incorrect
-Check the wiring between terminal 3 on the relay board and fuse from battery (in engine compartment (-90) or no.6 (91-) and the wiring between terminals 3 and 4 on the relay board and #4 and #21 on the MFI control module for breaks.
HB4
Checking The Control Signal
-Ignition on.
Connect a voltmeter between terminals 3 and 2 on the relay board.
-Operate the starter motor.
The voltmeter should read battery voltage.
If this value is OK
Try using a new relay.
If the reading is incorrect
-Check the wiring between terminal 2 on the relay board.
and #20 on the MFI control module for breaks.
-If the fault remains: Continue with connecting the test box HB6.
HB5
Checking The Fuel Pump (FP) Resistance
-Ignition off.
-Take apart the H02S 2-pole connector.
-Disconnect the interior lighting (760/960 fuse 26, 740/940 fuse 5).
Connect an ohmmeter between the right-hand terminal on fuse 4 and GND.
The ohmmeter should read 1-2 OHMS.
If this value is OK
-The readings indicate that there is no fault in the FP's electrical circuit. The FP has a mechanical fault. Try using a new FP.
HB6
Connecting The Test Box
Connect the test box and check the connections to GND.
-Continue with Checking the power supply (30 supply) HB7.
HB7
Checking The Power Supply (30 Supply)
-Connect the control module to the test box.
-Re-install system fuse.
-Ignition off.
Connect the voltmeter between #4 and #5 (GND).
The voltmeter should read battery voltage.
If this value is OK
-Check the voltage from ignition switch (15 supply) HR8.
If the reading is incorrect
-Check the wiring between #4 and system fuse (in engine compartment (-1990) or no.6 (1991-) for breaks.
HB8
Checking The Voltage From The Ignition Switch (15V supply)
-Ignition on.
Connect the voltmeter between #35 and #5 (GND). The voltmeter should read battery voltage. Check that there is a voltage reading when the starter motor is operating as well.
If this value is OK
-Check the engine speed signal from DI HB9.
If the reading deviates
Check the wiring between #35 and the ignition switch for breaks.
HB9
Checking The Engine Speed Signal From DI EZ 116 K
Connect a voltmeter between #1 and #5 (GND).
-Operate the starter motor.
The voltmeter should read 6-9 volts.
If this value is OK
-Check the injector circuit HB 10.
If the reading is Incorrect
-Check the wiring between MFI LH 2.4/LH 3.1 and DI EZ 116 K for breaks.
HB1O
Checking The Injector Circuit
-Ignition on.
Connect a voltmeter between #18 and #17 (power GND).
The voltmeter should read battery voltage.
If the reading is incorrect
-Check the wiring and connections between MFI #18 and terminal 3 on the suppressor relay for breaks or grounding.