Fuel Pump

Operation

Activates the fuel pump during engine cranking and while the engine is running.

When the ignition switch is set to the START position, the current flows, by way of the multiport fuel injection relay coil, from the ignition switch to ground. As a result, the multiport fuel injection relay switch is switched ON, and the power for activation of the fuel pump is supplied, by way of the multiport fuel injection relay switch, from the battery to the fuel pump.

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 multiport 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.




Inspection







Harness Inspection

Multiport Fuel Injection Relay Inspection

(1) Remove the multiport fuel injection relay.







(2) Use jumper wires and connect multiport fuel injection relay terminal 10 to the battery (+) terminal and terminal 8 to the battery (-) terminal.

Caution: Be very careful when connecting the jumper wires because the relay will be damaged if a mistake is made with the contact terminals.








(3) With battery (-) terminal jumper wire connected and disconnected, measure the Voltage at multiport fuel injection relay terminals 4 and 5.





(4) Use jumper wires to connect multiport fuel injection relay terminal 9 to the battery (+) terminal and terminal 6 to the battery (-)terminal.








(5) Disconnecting the jumper wire on the terminal (-) side of the battery, check whether or not continuity exists across terminals 2 and 3 of the multi port fuel injection relay.

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





(7) With the battery (-) terminal jumper wire connected and disconnected, measure the Voltage at multiport fuel injection relay terminal 2.
(8) Replace the multi port fuel injection relay if faulty.