LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Ford >> 1992 >> Probe GT, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System/Component Tests - EEC >> Fuel System >> Fuel System Testing >> Fuel System Circuitry Check
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Fuel System Circuitry Check

  1. Turn ignition on. Connect Green and Black wires of fuel pump test connector terminals together. Measure voltage at fuel pump (Black/Pink wire on 1.8L, or White/Yellow wire on 2.2L). If voltage is 10-14 volts, go step 9). If voltage is not 10-14 volts, measure voltage at specified terminal of fuel pump relay connector. See Fig 2 . See FUEL PUMP RELAY SPECIFICATIONS  . See Fig 4 for terminal identification. Repair circuit if voltage is not as specified.
    FUEL PUMP RELAY SPECIFICATIONS

    Terminal Ignition Position Voltage
    1.8L
    White/Red ON 10-14
    Purple START 10-14
    2.2L (MTX)
    Black/White ON 10-14
    Black/Red START 10-14
    2.2L (ATX)
    Black/White ON 10-14
    Black/Pink START 10-14
  2. If voltage is as specified, turn ignition off and remove fuel pump relay. Connect terminal "B" to battery voltage and terminal "A" to ground. See Figure . Check voltage at terminal "C" as follows.
    • With terminals "D" and "E" open, voltage at terminal "C" should be less than one volt.
    • With terminal "D" grounded and terminal "E" open, voltage at terminal "C" should be greater than 10 volts.
    • With terminal "D" open and terminal "E" grounded, voltage at terminal "C" should be less than 10 volts.
    • With terminals "D" and "E" grounded, voltage at terminal "C" should be greater than 10 volts.
  3. If voltage is not as specified, replace fuel pump relay. If voltage is as specified, measure resistance between relay box Black terminal and ground (Probe), or between fuel pump relay connector Black wire and ground (Escort and Tracer). See Fig 3 to locate Black terminal of fuel pump relay box on Probe.
    NOTE: On 2.2L turbo models, ECA wiring harness connector must be disconnected for step 4).
  4. If resistance is greater than 5 ohms, repair circuit. If resistance is less than 5 ohms, access Vane Airflow (VAF) meter door. On Probe, measure resistance between Light Green terminal of relay box and ground. On all other models, measure resistance between Light Green wire of fuel pump relay connector and ground.
  5. With VAF door closed, resistance should be greater than 10,000 ohms. With VAF door open, resistance should be less than 4 ohms. If resistance is not as specified, go to next step. If resistance is as specified, go to step 7) (on turbo models), or go to step 8) (on non-turbo models).
    Fig 1: Locating Fuel Pump Relay (1.8L)
    G91H08170Courtesy of FORD MOTOR CO.
    Fig 2: Locating Fuel Pump Relay (2.2L)
    G91J08171Courtesy of FORD MOTOR CO.
    Fig 3: Fuel Pump Relay Box Terminal ID (2.2L)
    G91B08172Courtesy of FORD MOTOR CO.
  6. Turn ignition off and disconnect VAF meter wiring harness connector. Measure resistance between designated terminals. See VAF FUEL PUMP SWITCH SPECIFICATIONS  . If resistance is not as specified, replace Black wire (1.8L), or Black/Light Green wire (2.2L).
    VAF FUEL PUMP SWITCH SPECIFICATIONS

    Door Position VAF Terminals Resistance (Ohms)
    1.8L
    Closed Lt. Green & Black Over 10,000
    Open Lt. Green & Black 0-5
    2.2L
    Closed Lt. Green & Black/Lt. Green Over 10,000
    Open Lt. Green & Black/Lt. Green 0-5
  7. On 2.2L turbo, install Breakout Box (T83L-50-EEC-IV), leaving ECA disconnected. With ignition off, measure resistance between test pins No. 53 and 60 of breakout box. Resistance should be greater than 10,000 ohms. Measure resistance between test pin No. 53 of breakout box and Light Green wire of fuel pump relay. See Fig 3 . Resistance should be less than 5 ohms. If resistance is not as specified, repair Light Green wire. If resistance is as specified, go to next step.
    NOTE: On 2.2L turbo, ECA must be disconnected for step 8).
  8. On all models, disconnect fuel pump relay connector. Turn ignition on. Measure voltage at Light Green (1.8L), or Black (2.2L) wire of fuel pump relay connector. See Fig 4 . On non-turbo models, if voltage is less than one volt, repair circuit between fuel pump and fuel pump relay. On turbo models, if voltage is less than one volt, replace ECA. On all models, if voltage is more than one volt, repair circuit short to power.
    Fig 4: Fuel Pump Relay Connector Terminal ID
    G91D08173Courtesy of FORD MOTOR CO.
  9. Turn ignition off. Remove fuel pump wiring harness connector. Measure resistance between Blue wire (1.8L) or White/Red wire (2.2L) and ground. If resistance is less than 5 ohms, release fuel pressure and attach fuel pressure gauge to fuel pump outlet hose. Disconnect fuel pump wiring harness connector. See Fig 5 .
  10. Connect jumper wire between Light Green wire and Black wire terminals of fuel pump test connector. Fuel pump should activate. Replace fuel pump if pressure is not 64-85 psi.
  11. If pressure is 64-85 psi, turn ignition off. Measure resistance between Black wire of fuel pump connector and ground. If resistance is less than 5 ohms, repeat step 1). If resistance is greater than 5 ohms, repair Black wire between fuel pump and inertia switch. If wire is okay, repair or replace inertia switch. See INERTIA SWITCH  under ENGINE SENSORS & SWITCHES.
Fig 5: Fuel Pump Wiring Harness Connector & Hoses
G91F08174Courtesy of FORD MOTOR CO.
scientia non olet · About LEMON Manuals