Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSGEO1991TRACKER LSI, AUTOMATICREPAIR AND DIAGNOSIS (SINGLE PAGE)ENGINE PERFORMANCESYSTEMENGINE CONTROLS - TESTS W/O CODESSYMPTOMSEXCESSIVE EXHAUST EMISSIONS
1991 Geo Tracker LSi, Automatic
Excessive Exhaust Emissions
1991 Geo Tracker LSi, AutomaticSECTION Excessive Exhaust Emissions
If vehicle fails emission test or has excessive "rotten egg smell", check the following items:
- Check fuel pressure.
- Check for leaking fuel injector if vehicle is running rich.
- Check canister purge and PCV valve operation.
- Check throttle position sensor or switch if vehicle is running rich.
- Check Manifold Absolute Sensor (MAP) if vehicle is running rich.
- Check EGR operation.
- Check for vacuum leaks.
- Ensure ignition timing and controls are working properly.
- Check for faulty spark plugs or spark plug wires.
- Check for exhaust leaks.
- Ensure engine warms to normal operating temperature.
- Ensure correct ECM application. Check with dealer for latest application information.
- Check for lead contaminated catalytic converter (look for removal of fuel filler neck restrictor).
- Check for defective oxygen sensor.
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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.