Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSFORD1991PROBE GL, STANDARDREPAIR AND DIAGNOSISENGINE PERFORMANCETESTING & DIAGNOSISENGINE CONTROLS - SYSTEM/COMPONENT TESTS - 2.2LFUEL SYSTEM TESTINGFUEL SYSTEM CIRCUITRY CHECK
1991 Ford Probe GL, Standard
Fuel System Circuitry Check
1991 Ford Probe GL, StandardSECTION Fuel System Circuitry Check
- 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 - 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.
- 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).
- 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.
- 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).
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.