Fuel Pump

Operation

The fuel pump is driven when the engine is cranking and while the engine is running. When the engine Is cranking and while the engine is running, the engine control module turns the power transistor ON to supply power to the multiport fuel injection relay coil. This causes the multiport fuel injection relay switch to turn ON, and current is supplied from the ignition switch via the multiport fuel injection relay switch to drive the fuel pump.








INSPECTION

While the engine is running, the engine control module switches ON the power transistor, after which current flows to the multiport fuel injection relay coil, and the power for activation of the fuel pump is supplied to the fuel pump.

When the multi port fuel injection relay switch is switched ON, battery Voltage is also applied to the engine control module, and so the engine control module detects the fact that the power for activation of the fuel pump is being supplied to the fuel pump.









Harness Inspection


Multiport Fuel Injection Relay Inspection





(1) Remove the multiport fuel injection relay.
(2) Check the continuity between the multiport fuel injection relay terminals.








(3) Use jumper leads to connect multiport fuel injection relay terminal 7 to the battery (+) terminal and terminal 5 to the battery (-) terminal.

Caution: When connecting the jumper leads, be careful not to mistake the connection terminals, as damage to the relay will result.





(4) Check the Voltage at multiport fuel injection relay terminal 1 while connecting and disconnecting the jumper lead at the battery (-) terminal.
(5) Use the jumper leads to connect multiport fuel injection relay terminal 8 to the battery (+) terminal and terminal 6 to the battery (-) terminal.








(6) Check the continuity between multiport fuel injection relay terminals 2-4 and terminals 3-4 while connecting and disconnecting the jumper lead at the battery (-) terminal.
(7) If there is a defect, replace the multi port fuel injection relay.

Multiport Fuel Injection Relay operation and inspection can be found under ECM Power and Ground Supply Circuits. ECM Power and Ground Supply Circuits