This procedure is only for vehicles with carburetors. Modern Ford E-150s almost exclusively use fuel injection, which doesn't have a mixture screw in the same way.
Before You Begin:
* Identify the carburetor: Locate the carburetor on your engine. It's usually a large, cast-metal component on top of the engine.
* Consult your owner's manual or a repair manual specific to your E-150's year and engine: This will provide detailed diagrams and specifications for your particular carburetor. Different carburetors have different adjustments.
* Gather tools: You'll need a small, flat-blade screwdriver (usually a jeweler's screwdriver), and possibly a vacuum gauge. A vacuum gauge is highly recommended for accurate adjustment.
Adjustment Procedure (General):
1. Warm-up the engine: Let the engine run until it reaches normal operating temperature. A cold engine will not provide accurate readings.
2. Locate the mixture screws: These are usually small screws located on the carburetor's body, often near the throttle linkage. They are frequently covered by a protective cap.
3. Initial Setting (If Unknown): If you don't know the previous setting, carefully count the number of turns the screw is out from fully seated (lightly seated). This serves as a baseline for comparison.
4. Vacuum Gauge Method (Recommended): Connect a vacuum gauge to a vacuum port on the intake manifold (consult your manual for location). Idle the engine and adjust the mixture screw in small increments (1/8 to 1/4 turn at a time). Observe the vacuum gauge reading. The ideal setting will usually yield the highest vacuum reading at idle.
5. Without Vacuum Gauge Method (Less Accurate): With the engine warmed up and idling, slowly turn the mixture screw in (clockwise) and out (counterclockwise), listening to the engine's idle quality. A lean mixture will often result in a higher idle speed but may sound rough, while a rich mixture will often result in a lower idle speed and may sound slightly "boggy". You're aiming for a smooth, steady idle. This method is highly subjective and less precise.
6. Fine-tuning: After finding a setting that produces either the highest vacuum (with a vacuum gauge) or the smoothest idle (without), make small adjustments to fine-tune.
7. Test Drive: After adjusting, take the vehicle for a test drive to verify the adjustment is effective. Look for improved fuel economy, smooth acceleration, and consistent idle. If the adjustment is not optimal, repeat the process.
Important Considerations:
* Count the turns: Always carefully count the number of turns you make, keeping track of your adjustments.
* Small adjustments: Make only small adjustments at a time; larger adjustments can easily throw things off.
* Engine damage: Incorrect adjustments can lead to engine damage. Proceed with caution.
* Emissions: Improper carburetor adjustment will negatively impact your vehicle's emissions.
Again, if you are uncomfortable with this procedure, consult a professional mechanic. Carburetor adjustment is a skill that requires practice and experience. Incorrect adjustment can cause significant engine problems.
