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HOMESERVICE MANUALSFORD1994TAURUS GL, 4D SEDAN, 3.8 4REPAIR AND DIAGNOSIS (SINGLE PAGE)ENGINE PERFORMANCETESTING & DIAGNOSISENGINE CONTROLS - TESTS W/CODES - EEC-IV (3.8L)CIRCUIT TESTSCIRCUIT TEST J - FUEL PUMP CIRCUIT (RELAY & INERTIA SWITCH)NO START
1994 Ford Taurus GL, 4D Sedan, 3.8 4

No Start

1994 Ford Taurus GL, 4D Sedan, 3.8 4SECTION No Start
  • IFS switch circuit open or not reset.
  • Open circuit in or between PCM and fuel pump.
  • Faulty ground connection at fuel pump.
  • Faulty fuel pump.

If engine starts, go to next step. If engine does not start, go to step 15).

11) Check Fuel Pump Operation  Turn ignition on. Wait 5 seconds. Listen for fuel pump operation. If fuel pump is off, go to step 13). If fuel pump is on, go to next step.

12) Check For Fuel Pump Relay Always Closed  Turn ignition off. Disconnect fuel pump relay. Turn ignition on. If fuel pump is off with relay disconnected, replace fuel pump relay and repeat QUICK TEST. If fuel pump is on with relay disconnected, repair short to power in POWER-TO-PUMP or FPM circuit. (For models with relay block, also check fuel pump prime plug circuit). Repeat QUICK TEST.

13) Check Continuity Of Fuel Pump Monitor (FPM) Circuit  Turn ignition off. Disconnect PCM 60-pin connector. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Install EEC-IV Breakout Box (T83L-50-EEC-IV), leaving PCM disconnected. Disconnect fuel pump relay. Measure resistance between test pin No. 8 at breakout box and POWER-TO-PUMP circuit at fuel pump relay wiring harness connector. If resistance is less than 5 ohms, go to step 25) (dual HO2S) or replace PCM and repeat QUICK TEST (single HO2S). If resistance is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components, and repeat QUICK TEST.

NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 13) to step 15). No test procedures have been omitted.

15) Check IFS Switch  Turn ignition off. Disconnect fuel pump IFS switch. Ensure switch is reset. Measure resistance of IFS switch. If resistance is less than 5 ohms, check for open in POWER-TO-PUMP circuit, poor fuel pump ground or faulty fuel pump. If resistance is 5 ohms or more, reset or replace IFS switch. Repeat QUICK TEST.

NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 15) to step 20). No test procedures have been omitted.

20) Code 543  Code 543 indicates fuel pump secondary circuit failure between B+ circuit and FPM connection to POWER-TO-PUMP circuit. Following are possible causes:



  • Open circuit between B+ and FPM connection to POWER-TO-PUMP circuit.
  • Fuel pump relay contacts are always open.
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.