Engine Performance Safety Precautions

1990 Toyota 4Runner 2D Utility, 3.0 V, StandardSECTION Engine Performance Safety Precautions
  • Always refer to Emission Decal in engine compartment before servicing vehicle. If manual and decal differ, always use decal specifications.
  • Do not allow or create a condition of misfire in more than one cylinder for an extended period of time. Damage to converter may occur due to loading converter with unburned air/fuel mixture.
  • Always turn ignition off and disconnect negative battery cable BEFORE disconnecting or connecting computer or other electrical components.
  • DO NOT drop or shock electrical components such as computer, airflow meter, etc.
  • DO NOT use fuel system cleaning compounds that are not recommended by the manufacturer. Damage to gaskets, diaphragm materials and catalytic converter may result.
  • Before performing a compression test or cranking engine using a remote starter switch, disconnect coil wire from distributor and secure it to a good engine ground, or disable ignition.
  • Before disconnecting any fuel system component, ensure fuel system pressure is released.
  • Use a shop towel to absorb any spilled fuel to prevent fire.
  • DO NOT create sparks or have an open flame near battery.
  • If any fuel system components such as hoses or clamps are replaced, ensure they are replaced with components designed for fuel system use.
  • Always reassemble throttle body components with new gaskets, "O" rings and seals.
  • If equipped with an inertia switch, DO NOT reset switch until fuel system has been inspected for leaks.
  • Wear safety goggles when drilling or grinding.
  • Wear proper clothing which protects against chemicals and other hazards.
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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.