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Fuel System Pressure Test: TBI

  1. Turn ignition off for 10 seconds. Turn ignition on, and listen at fuel tank for fuel pump operation. Pump should run 2 seconds (20 seconds on models equipped with fuel module). If fuel pump runs, go to next step. If fuel pump does not run, go to step 7).
  2. If fuel pump runs, turn ignition off. Verify fuel tank has fuel. Relieve fuel pressure. See FUEL SYSTEM PRESSURE RELIEF . Remove air cleaner, and plug air cleaner vacuum ports (if equipped). Disconnect fuel line between throttle body and fuel filter. Install Fuel Pressure Gauge (J-29658A) and Adapter (J-2968A-85) between steel fuel line and flexible hose, ahead of in-line fuel filter.
  3. Turn ignition on, and note reading on pressure gauge. If fuel pressure is 9-13 psi (.63-.91 kg/cm2 ), no problems are present. If pressure is less than 9 psi (.63 kg/cm2 ), go to step 5). If pressure is greater than 13 psi (.91 kg/cm2 ), turn ignition off, and bleed fuel pressure. Disconnect fuel return line downstream of pressure gauge. Insert return line into a gasoline container.
  4. Turn ignition on. If pressure is now 9-13 psi (.63-.91 kg/cm2 ), correct restriction in fuel return line between disconnected point and fuel tank. If fuel pressure is greater than 13 psi (.91 kg/cm2 ), check for restricted return line (including fuel filter) downstream of pressure gauge. If no restrictions are present, replace fuel pressure regulator (TBI 700) or fuel meter cover/pressure regulator (TBI 220).
  5. If fuel pressure was less than 9 psi (.63 kg/cm2 ), check for restricted line between in-tank fuel pump and pressure regulator. If fuel line is okay, disconnect injector connector. Turn ignition on. Gradually pinch fuel pressure gauge outlet hose. Note pressure.
    CAUTION: DO NOT  pinch off fuel return line completely. DO NOT  allow fuel pressure build-up to exceed specification, as damage to fuel pressure regulator may occur.
  6. If pressure is greater than 13 psi (.91 kg/cm2 ), replace fuel pressure regulator (TBI 700) or fuel meter cover/pressure regulator (TBI 220). If pressure is less than 9 psi (.63 kg/cm2 ), check for faulty fuel pump or incorrect part. Check fuel pump coupling hose and pump inlet filter in fuel tank. On models with dual fuel tanks, check for faulty fuel tank selector valve and meter switch.
  7. If fuel pump did not run in step 1), apply 12 volts to fuel pump test connector. For fuel pump test connector location, see underhood engine component views under COMPONENT LOCATIONS in SYSTEM/COMPONENT TESTS article in this section. If fuel pump now runs, repair open in fuel pump relay drive or power circuit or repair faulty fuel pump relay. To test relay, see FUEL PUMP RELAY in SYSTEM/COMPONENT TESTS article in this section.
  8. If fuel pump does not run with 12 volts applied to fuel pump test connector, repair open in fuel pump power or ground circuit or repair faulty fuel pump.
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