Single Diaphragm Valve

1990 Toyota 4Runner 2D Utility, 3.0 V, StandardSECTION Single Diaphragm Valve
  1. Check all vacuum hoses for correct routing. Warm engine to operating temperature. Disconnect vacuum hose from EGR valve.
  2. With engine at idle, apply intake manifold vacuum to EGR valve. On systems equipped with a modulator and/or auxiliary control valve, engine should run rough or carburetor should make bubbling noise.
  3. On systems not equipped with a modulator and/or auxiliary control valve, increase engine speed to 3000-3500 RPM. Carburetor should make bubbling noise. If bubbling noise is not heard, check other EGR system controls. See appropriate article.
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.