Fuel Pump: Testing and Inspection

Fuel Pump Control Circuit Diagram:

The following procedure should be used to check for a "NO FUEL" condition. Refer to the schematic diagram and test the circuit with the diagnostic chart.

Wire color code identification:

L: Blue
B: Black
Y: Yellow
G: Green
R: Red
W: White
Br: Brown
Lg: Light green
Gr: Gray

Fuel Pump Control Circuit Diagnostic Chart:

FUEL PUMP CONTROL SYSTEM DIAGNOSTIC CHART

CHECK OPERATION OF FUEL PUMP
Turn the key "ON". Fuel pump should operate for two (2) seconds after turning the key from "Off" to "ON".

CHECK VOLTAGE AND RESISTANCE OF FUEL PUMP AND RELAY
1. Remove fuel pump relay.
2. Using an ohmmeter, check the resistance of relay coil.

Connector & terminal: Resistance:
(F78)1-(F78)3 60 - 80 Ohm @ 20° C (68° F)

3. Connect 12 VDC to relay coil terminals and measure the resistance between the switched terminals.

Connector & terminal: Resistance:
(F78)2-(F78)4 Below 1 Ohm
4. Reinstall the relay.


CHECK FUEL PUMP RELAY CIRCUIT
1. Turn key "ON".
2. Using a voltmeter, measure the voltage between fuel pump relay connector and ground.

Connector & terminal: Voltage:
(F78)3-Ground Above 9V

CHECK VOLTAGE BETWEEN ECU CONNECTOR AND GROUND
1. Turn key "ON".
2. Using a voltmeter, check the voltage for two (2) seconds after turning the key from "OFF" to "ON". (Back probe the ECU connector.)

Connector & terminal: Voltage:
(F119)18-Ground Above 9V

3. Check voltage AFTER key has been ON for two (2) seconds.

Connector & terminal: Voltage:
(F119)18-Ground Below 2.5V

Fuel Pump Connector:

CHECK TERMINAL VOLTAGE TO FUEL PUMP
1. Disconnect fuel pump connector.
2. Turn key "ON".
3. Using a voltmeter, check the voltage for two (2) seconds after turning the key from "OFF" to "ON".

Connector & terminal: Voltage:
(R29)2-Ground Above 9V

4. Check voltage AFTER key has been ON for two (2) seconds.

Connector & terminal: Voltage:
(R29)2-Ground Below 2.5V

CHECK FUEL PUMP
Connect 12V to fuel pump connector and confirm fuel pump operates.

Connector & terminal: Battery terminal
(R29)2 Positive terminal
(R29)1 Negative terminal