1991 Mercury Cougar LS, 3.8 4FACTORY OEM SERVICE PROCEDURE

Spark Check

Check EEC-IV system for fault codes and repair if necessary. See Quick Test procedure in the appropriate TESTS W/CODES article in this section. If no fault codes are retrieved and vehicle is a no-start, using a Neon Bulb Spark Tester (D89P-6666-A), check for spark at each spark plug wire while cranking. If spark is consistent and equal at each spark plug (one spark per crankshaft revolution), go to appropriate ignition system in the appropriate SYSTEM/COMPONENT TESTS article in this section.

Fig 1: Distributorless Ignition System Electrical Schematic
G90C09247Courtesy of FORD MOTOR CO.
Factory Service Tools

Use the Manual With the Right Hardware

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • β€’ You smell fuel, burning insulation, or see smoke.
  • β€’ Brakes feel soft, pull hard to one side, or make grinding noises.
  • β€’ The engine overheats, stalls repeatedly, or misfires under load.
  • β€’ You are missing required tools, torque specs, or safe lifting equipment.
  • β€’ You are not confident in the next step or safety outcome.

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