That said, if you're determined to try it yourself, here's a general overview. This is not a comprehensive guide and may not apply to your specific carburetor type. You'll need to consult a repair manual specific to your Blazer's engine and carburetor for precise instructions and diagrams.
Important Note: The 1994 Blazer likely has a TBI (Throttle Body Injection) system, *not* a traditional carburetor. TBI is a simpler form of fuel injection, and adjustments are different. If you have TBI, these instructions won't apply. Verify you actually have a carburetor before proceeding.
If you definitively have a carburetor (unlikely on a '94), the general process involves these steps:
1. Identify your carburetor: Different manufacturers (Rochester, Carter, etc.) have different adjustment screws. Find the make and model of your carburetor.
2. Locate the adjustment screws: These are usually on the top of the carburetor. You'll typically find idle speed screws (adjusts RPM at idle), idle mixture screws (adjusts air/fuel ratio at idle), and possibly fast idle screws (adjusts RPM when cold).
3. Warm up the engine: Let the engine run until it reaches normal operating temperature.
4. Adjust the idle speed: With a warmed-up engine, adjust the idle speed screw to achieve the manufacturer's specified idle speed (usually found in your repair manual).
5. Adjust the idle mixture: This is the most crucial and difficult part. You'll need to adjust each idle mixture screw (usually two) incrementally, turning them slightly (1/8 to 1/4 turn at a time) and observing the engine's response. Listen for smooth running and look for a smooth idle. Turning the screw in (clockwise) leans the mixture (less fuel), and turning it out (counter-clockwise) enriches the mixture (more fuel). You'll likely need to adjust both screws alternately to find the optimal setting for a smooth, consistent idle. An exhaust gas analyzer can help with this, but it's not essential for a rough adjustment.
6. Check for vacuum leaks: Any vacuum leaks can significantly affect carburetor performance. Inspect all vacuum hoses and connections for cracks or leaks.
7. Fast Idle adjustment (if applicable): Adjust the fast idle cam to ensure a smooth transition from cold start to normal idle.
8. Test drive: After making adjustments, test drive your Blazer to evaluate performance. If the engine stumbles, hesitates, or runs poorly, re-adjust the screws as needed.
Again, this is a highly simplified overview. Improper adjustment can cause serious engine problems. Consult a detailed repair manual specific to your vehicle's engine and carburetor for the correct procedure. Consider seeking professional help if you're not comfortable with this task. A poorly adjusted carburetor can result in significant damage and higher repair bills down the road.
