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Circuit Test V

To prevent replacement of good components, be aware that the following non-EEC related areas may be at fault: fuel lines, fuel filters, throttle body, fuel pump or contaminated fuel.

  1. Install fuel pressure gauge. Check if fuel pump runs. Cycle key from off to on several times. DO NOT  crank engine. Pump should operate each time key is on. If pump runs as indicated, check electric fuel pump system for problems. If pump does not run as indicated, go to next step.
  2. Turn key off and wait 10 seconds. Disconnect ECA 60-pin connector. Inspect for and repair any damaged wiring. Install breakout box and connect ECA. Turn key on, leaving engine off. Set DVOM on 20 volt scale. Measure voltage between test pins No. 37 and 40, and between test pins No. 57 and 60. If either reading is less than 10.5 volts, go to CIRCUIT TEST B  , step 1). If both readings are 10.5 volts or more, go to next step.
  3. Turn key off and wait 10 seconds. Leave breakout box installed and ECA connected. Locate and disconnect fuel pump inertia switch. Set DVOM on 200-ohm scale and measure switch resistance. If reading is 5 ohms or more, replace inertia switch and repeat QUICK TEST  . If reading is less than 5 ohms, go to next step.
  4. Turn key on, leaving engine off. Leave breakout box installed and ECA connected. Locate fuel pump relay. Set DVOM on 20 volt scale. Measure voltage between chassis ground and power-to pump(s) circuit at fuel pump relay while cranking engine. If reading is less than 8 volts, go to step 6). If reading is 8 volts or more, go to next step.
  5. Turn key on, leaving engine off. Leave breakout box installed and ECA connected. Locate fuel pump(s). Set DVOM on 20-volt scale. Measure voltage between chassis ground and power-to-pump(s) circuit at fuel pump(s) while cranking. If reading is 8 volts or more, service electric fuel pump(s). If reading is less than 8 volts, repair open in power-to-pump(s) circuit and repeat QUICK TEST  .
  6. Turn key on, leaving engine off. Leave breakout box installed and ECA connected. Locate fuel pump relay. Set DVOM on 20 volt scale. Measure voltage between chassis ground and V BATT circuit at fuel pump relay. If reading is less than 10.5 volts, repair open in V BATT circuit between fuel pump relay and battery positive post. Repeat QUICK TEST  . If reading is 10.5 volts or more, go to next step.
  7. Turn key on, leaving engine off. Leave breakout box installed and ECA connected. Locate fuel pump relay. Set DVOM on 20 volt scale. Measure voltage between chassis ground and V POWER circuit at fuel pump relay. If reading is less than 10.5 volts, repair open in V POWER circuit between fuel pump relay and ECA. Repeat QUICK TEST  . If reading is 10.5 volts or more, go to next step.
  8. Turn key off and wait 10 seconds. Leave breakout box installed and ECA connected. With DVOM on 200-ohm scale, measure resistance between fuel pump circuit at pump relay and test pin No. 22. If reading is 5 ohms or more, repair open in fuel pump circuit. Repeat QUICK TEST  . If reading is less than 5 ohms, go to next step.
  9. Turn key off. Leave breakout box installed and disconnect ECA. Disconnect fuel pump relay. With DVOM on 200,000-ohm scale, measure resistance between test pin No. 22 and test pins No. 40 and 60. If reading is less than 10,000 ohms, repair short in fuel pump circuit. Repeat QUICK TEST  . If reading is 10,000 ohms or more, go to next step.
  10. Turn key off and wait 10 seconds. Leave breakout box installed. Leave fuel pump relay and ECA disconnected. With DVOM on 200,000-ohm scale, measure resistance between test pin No. 22 and test pins No. 37 and 57. If reading is less than 10,000 ohms, repair short to power in fuel pump circuit. Connect ECA and attempt to start engine. If engine does not start, replace ECA. Repeat QUICK TEST  . If reading is 10,000 ohms or more, connect fuel pump relay and go to next step.
  11. Leave breakout box installed and ECA disconnected. Install a jumper wire between test pin No. 22 and either test pin No. 40 or No. 60. Set DVOM on 20-volt scale. Turn key on, leaving engine off. Measure voltage between chassis ground and power-to-pump(s) circuit at fuel pump relay. If reading is 10.5 volts or more, replace ECA and repeat QUICK TEST  . If reading is less than 10.5 volts, replace fuel pump relay. Connect ECA and repeat QUICK TEST  .
  12. Turn key off. Remove fuel pump relay. If fuel pump turns off, replace fuel pump relay. Repeat QUICK TEST  . If fuel pump does not turn off, repair short to power-to-pump(s) circuit.
Fig 1: Fuel Pump (Inertia Switch Circuits
G48114
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