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 MANUALSMERCURY1991TRACER BASE, 4D SEDAN, AUTOMATICREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 48 (ENGINE CONTROLS - BASIC TESTING - V6)FUEL SYSTEMFUEL PRESSUREMODELS WITHOUT EEC-V
1991 Mercury Tracer Base, 4D Sedan, Automatic
Models Without EEC-V
1991 Mercury Tracer Base, 4D Sedan, AutomaticSECTION Models Without EEC-V
WARNING: This page does not describe the selected car, but rather 9 other vehicles, including the 1994 Mercury Topaz, 1994 Mercury Sable, 1994 Mercury Cougar, 1994 Lincoln Continental, and 1994 Ford Thunderbird. However, it is still accessible from the selected car via links, so may be relevant.
- Release fuel pressure. Install fuel pressure gauge. Connect a jumper wire between fuel pump test terminal at the Data Link Connector (DLC) and ground. See Fig 1. Turn ignition on, but DO NOT start engine. This activates the fuel pump.
- Measure and record Key On, Engine Off (KOEO) fuel pressure. Start engine. Measure and record Key On, Engine Running (KOER) fuel pressure. For fuel pressure specifications, see FUEL PRESSURE SPECIFICATIONS article. Turn ignition off and monitor fuel pressure for one minute. Fuel pressure should not drop more than 5 psi (34 kPa).
- If fuel pressure is within specification, test is complete. If fuel pressure is not within specification, check fuel filter and lines for restriction(s). Repair or replace as necessary. If fuel pressure is still not within specification, install fuel pressure gauge (if removed).CAUTION: Inspect fuel system for leaks or damage before testing fuel pump.
- Start engine and observe fuel pressure gauge. Gently squeeze fuel return hose. If fuel pressure increases while squeezing fuel return hose, replace fuel pressure regulator. If fuel pressure does not change while squeezing fuel return hose, check for plugged fuel inlet strainer or defective fuel pump. Repair as necessary.NOTE: For additional fuel system testing information, Proceed to appropriate SYSTEM/COMPONENT TESTS article as listed below. On EEC-IV & EEC-V equipped models, see appropriate TESTS W/CODES article as listed below for diagnostic procedure of PCM controlled fuel pump circuits.
- SYSTEM/COMPONENT TESTS - EEC-IV (3.0L) (for Sable, Taurus, Tempo & Topaz)
- SYSTEM/COMPONENT TESTS - EEC-IV (3.2L SHO) (for Taurus)
- SYSTEM/COMPONENT TESTS - EEC-IV (3.8L) (for Continental, Cougar, Sable, Taurus & Thunderbird)
- SYSTEM/COMPONENT TESTS - EEC-V (for Mustang)
- TESTS W/CODES - EEC 2.5L (for Probe)
- TESTS W/CODES - EEC-V (3.8L) (for Mustang)
- TESTS W/CODES - EEC-IV (3.8L) (for Continental, Cougar, Mustang, Sable, Taurus & Thunderbird)
- TESTS W/CODES - EEC-IV (3.2L SHO) (for Taurus)
- TESTS W/CODES - EEC-IV (3.0L) (for Sable, Taurus, Tempo & Topaz)
- TESTS W/CODES - EEC-V (3.8L) (for Mustang)
RENDER: 1.0x
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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.