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 MANUALSFORD1987BRONCO 4.9 Y, STANDARD, T18REPAIR AND DIAGNOSIS (SINGLE PAGE)ENGINE PERFORMANCETESTING & DIAGNOSISFUEL PUMP - ELECTRICTESTINGIN-TANK FUEL PUMP7.5L ENGINE
1987 Ford Bronco 4.9 Y, Standard, T18
7.5L Engine
1987 Ford Bronco 4.9 Y, Standard, T18SECTION 7.5L Engine
- Check for adequate fuel supply. Check for fuel leakage from lines and fittings. Replace lines and/or fitting as necessary.
- Remove fuel pump cut-off relay connector. Check for voltage between Yellow wire at connector and ground. If 12 volts are present, go to next step. If voltage is not present, check inertia switch and wiring. Reset switch (if necessary).
- Connect voltmeter between Pink/Black wire of connector and ground. Crank engine momentarily, and note voltage reading. If 10-12 volts are present while cranking, go to step 4. If voltage is less than 10 volts, check fusible link and resistance wire.
- With ignition off, check continuity between Pink/Black wire and ground. If continuity exists, go to step 5. If continuity does not exist, check tank selector relay (if equipped). If relay is okay, or is not used, go to step 5.
- Check continuity across fuel pump terminals and wiring harness. If continuity exists, go to step 6. If continuity does not exist, replace fuel pump/sending unit assembly.
- Attach relay connector. Connect voltmeter leads between Pink/Black wire and ground. Crank engine until oil pressure is built up, turn ignition back to "RUN" position, and note voltmeter reading.
- If voltage (10-12 volts) remains steady, perform FUEL PUMP PRESSURE TEST . If voltage (10-12 volts) is not steady, or never existed, check relay circuit and oil pressure switch.
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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.