1979 Mazda B2000 BaseFACTORY OEM SERVICE PROCEDURE

1979 Models (Servo Diaphragm Test)

  1. Connect tachometer to engine. Start and warm engine to normal operating temperature. Stop engine and remove air cleaner.
  2. Detach intake manifold vacuum hose from 3-way solenoid and detach 3-way solenoid vacuum hose from servo diaphragm. Connect intake manifold vacuum hose directly to servo diaphragm.
  3. On 626, detach and plug distributor-to-carburetor vacuum tube at distributor. On all models, start engine. Increase engine speed and allow speed then decrease to idle.
  4. With servo diaphragm hooked directly to intake manifold, engine should idle at 1000-1100 RPM. If vehicle is equipped with air conditioning, it will idle at approximately 1200 RPM.
  5. If speed is not to specifications, turn throttle positioner adjusting screw located on linkage near end of servo diaphragm link on carburetor. If setting cannot be obtained, replace servo diaphragm.
Factory Service Tools

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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.

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