1989 Geo Tracker Base, AutomaticFACTORY OEM SERVICE PROCEDURE

System Performance Test 1 (Spectrum)

  1. Set parking brake. Place transmission in "P" (A/T) or "N" (M/T) and block wheels. Start engine. Disconnect and plug vacuum hose from charcoal canister and vent switch valve. Connect tachometer. Disconnect mixture control solenoid at 3-pin carburetor connector. Ground mixture control solenoid dwell terminal.
  2. Run engine at 3000 RPM. Keep throttle constant and reconnect mixture control solenoid. Note RPM. If RPM dropped more than 100 RPM, go to step 3). If RPM dropped less than 100 RPM or increased, check mixture control solenoid connections or repair carburetor. Remove ground from mixture control solenoid dwell terminal before returning to idle.
  3. Disconnect idle set connector and connect dwell meter (6-cyl. scale) to mixture control solenoid dwell terminal. Warm engine at part throttle until upper radiator hose is warm. Return engine to idle and note dwell.
  4. If dwell is fixed less than 15 degrees, go to TEST 2. If dwell is fixed at 15-50 degrees, go to TEST 3. If dwell is fixed greater than 50 degrees, go to TEST 4. If dwell is varying, go to step 5).
  5. Check dwell at 3000 RPM. If dwell is varying between 10-50 degrees, check fuel cut-off system in TEST 6. If dwell is not between 10-50 degrees, check TPS or repair carburetor. If no trouble is found, clear trouble codes.
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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.