LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Ford >> 1991 >> Probe GL, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System/Component Tests - 2.2L >> Fuel System Testing >> Fuel System Circuitry Check
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Fuel System Circuitry Check

  1. With ignition on and fuel system test terminals connected, 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, as described in FUEL PUMP RELAY SPECIFICATIONS  , at fuel pump relay connector. See Fig 4 for terminal identification. Repair circuit if voltage is not as specified.
    FUEL PUMP RELAY SPECIFICATIONS

    Terminal Ignition Position Voltage
    1.8L
    W/R ON 10-14
    P START 10-14
    2.2L (M/T)
    BK/W ON 10-14
    BK/R START 10-14
    2.2L (A/T)
    BK/W ON 10-14
    BK/PK 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 less than 10 volts.
    • With terminal "D" open and "E" grounded, voltage at terminal "C" should be greater 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 BK terminal and ground (Probe), or between fuel pump relay connector Black wire and ground (all others). See Fig 3 to locate BK 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 VAF meter door. On Probe, measure resistance between LG terminal of relay box and ground. On all others, 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 step 6). If resistance is as specified, go to step 7) (turbo), or go to step 8) (non-turbo).
    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: Identifying Fuel Pump Relay Box Terminals (Probe)
    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 Light Green & Black Over 10,000
    Open Light Green & Black 0-5
    2.2L
    Closed Light Green & Black/Light Green Over 10,000
    Open Light Green & Black/Light 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 No. 60 of breakout box. Resistance should be greater than 10,000 ohms. Measure resistance between test pin No. 53 of breakout box and LG circuit (Light Green wire) of fuel pump relay. See Fig 3 for location of LG circuit. Resistance should be less than 5 ohms. If resistance is not as specified, repair LG circuit (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 connector terminal LG (Light Green wire on the 1.8L), or BK (Black wire on the 2.2L). See Fig 4 On non-turbo engines, if voltage is less than one volt, repair circuit between fuel pump and fuel pump relay. On turbo engines, 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: Identifying Fuel Pump Relay Connector Terminals
    G91D08173Courtesy of FORD MOTOR CO.
  9. Turn ignition off. Remove fuel pump wiring harness connector. Measure resistance between Black 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. On 1.8L engines, connect jumper wire between fuel pump connector Black wire and Black/White wire terminals. On 2.2L engines, connect jumper wire between fuel pump connector White/Red and White/Yellow wire terminals. 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 fuel pump connector Blue wire (1.8L) or White/Red wire (2.2L) and ground. If resistance is less than 5 ohms, repair Blue wire (1.8L) or White/Red wire (2.2L) between fuel pump and inertia switch. Repeat step 1). If resistance is greater than 5 ohms, repair or replace inertia switch. See INERTIA SWITCH under ENGINE SENSORS & SWITCHES.
Fig 5: Identifying Fuel Pump Wiring Harness Connector & Hoses
G91F08174Courtesy of FORD MOTOR CO.
scientia non olet · About LEMON Manuals