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Fuel Pump Circuit Tests: JUSTY

  1. Check Fuel Pump Operation  - Verify fuel pump operation for 2 seconds after turning ignition on. If fuel pump operates for 2 seconds, check fuel injector circuit. See JUSTY under FUEL INJECTOR CIRCUIT TESTS  . If fuel pump does not operate, go to next step.
  2. Check Fuel Pump Relay Operation  - Disconnect fuel pump relay connector and remove fuel pump relay from bracket. Measure resistance of relay coil connector terminals No. 1 (Blue/Black wire) and No. 3 (Red wire). Fuel pump relay is okay if resistance is 60-80 ohms at 68°F (20°C). Measure resistance between fuel pump relay terminals No. 2 and 4. There should be no continuity. Connect battery voltage between fuel pump relay terminals No. 1 and 3. Measure resistance between fuel pump relay terminals No. 2 and 4. Resistance should be less than one ohm. If resistance is not as specified, replace fuel pump relay. If resistance is as specified, install fuel pump relay on bracket, connect fuel pump connector and go to next step.
  3. Check Fuel Pump Relay Power Line Circuit  - Turn ignition on. Measure voltage between fuel pump relay connector terminal No. 3 (Red wire) and ground. If 9 volts are present, go to next step. If 9 volts are not present, repair harness or connectors as necessary.
  4. Check Voltage Between ECU 26-Pin Connector & Ground  - Turn ignition on for 2 seconds and measure voltage between ECU 26-pin connector terminal No. 18 (Blue/Black wire) and ground. Voltage should be 2.5 volts while ignition is on. After 2 seconds, turn ignition off and measure voltage. Voltage should be 9 volts. If voltage readings are as specified, go to next step. If voltage readings are not as specified, check ECU harness, connector and ground wire. Repair harness or connectors as necessary. If harness and connectors are okay, replace ECU.
  5. Check Voltage At Fuel Pump Terminal  - Disconnect fuel pump/gauge connector. Turn ignition on for 2 seconds and measure voltage between fuel pump/gauge connector terminal No. 2 and ground. If voltage is greater than 9 volts, go to next step. If voltage is less than 9 volts, repair harness or connectors as necessary.
  6. Check Fuel Pump Operation  - Connect battery voltage to fuel pump/gauge connector terminal No. 2 and a jumper wire from fuel pump/gauge connector terminal No. 1 to ground. If fuel pump operates, repair fuel pump/gauge ground circuit. If fuel pump does not operate, repair fuel pump.
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