What Are the Causes of a Too Lean Air-Fuel Mixture in a Car?
1 Answers
Causes of a too lean air-fuel mixture in a car: 1. The carburetor float is stuck or improperly adjusted, resulting in a too low fuel level in the float chamber. 2. The carburetor inlet fuel filter screen is too dirty. 3. The carburetor main jet or main fuel passage is clogged, or the main jet adjustment needle is screwed in too much. 4. The carburetor or intake/exhaust manifold gasket is damaged, screws are loose, or the throttle shaft is severely worn, causing air leaks. 5. The carburetor fuel supply is insufficient. Diagnosis and troubleshooting of a too lean air-fuel mixture: 1. Check if the carburetor fuel level is too low. If it is, adjust it to normal. 2. If the fuel level is normal but the condition improves when the choke is partially closed, check for air leaks at the intake manifold gasket, carburetor base, throttle shaft, etc. 3. Check if the carburetor main jet or main fuel passage is clogged. 4. Check if the carburetor main jet adjustment needle is screwed in too much. 5. If the fuel level is adjusted to normal but becomes too low again after the engine runs at medium or high speed for a while, the carburetor inlet fuel filter screen may be clogged or the external fuel supply is insufficient. Follow the diagnostic steps for insufficient fuel supply to check.
