There is not really a set fuel air mixture. Each engine will be different even if they are the same engine during the build process they are set specifically to the engine.
The MAP sensor measures air flow for your car's computer. The computer uses air flow to set fuel flow for the correct fuel/air mixture.
Fuel pump going out throttle body needs replaced air fuel mixture not set right.
Do you mean Oxygen sensor? If so, it measures the air fuel mixture in the exhaust to help the computer set the proper amount of fuel to be added to keep the mixture at the proper level.
Could be that the air/fuel mixture is set too lean. Needs adjustment.
Check your timing and if it is a carb, check to make sure the air fuel mixture is set properly.
idle set too low, adjust the fuel to air mixture on a carb vehicle.if fuel injected, your injectors may need cleaned.Kadius1964~blog me.
To set the fuel and air mixture on a carburetor for a 1400 Nissan, locate the air-fuel mixture screw, usually found on the side of the carburetor. Start by turning the screw gently clockwise until it lightly seats, then back it out to the manufacturer’s recommended position, often around 1.5 to 2 turns. Adjust the idle speed screw to achieve a stable idle, and make fine adjustments to the mixture screw while the engine is running until you reach a smooth idle. Always consult the specific service manual for your engine model for precise settings.
Turn it all the way in and then back out 1 1/2 turns
Turn the fuel screw all the way in, the turn it out two and a half turns. Turn the pilot air screw half a turn in to enrich the fuel mixture and keep it from stalling at low speeds if needed. If the fuel mixture is too lean then turn the fuel screw out a little, like a half turn.
The air mixture screw on a Yamaha Raptor 350 is typically set at around 1.5 turns out from fully closed as a starting point. You may need to adjust it slightly to fine-tune the air-fuel mixture for optimal performance. It's best to consult the user manual or a mechanic for specific recommendations based on your riding conditions.
See the attached link below. The high altitude compensator opens at high elevation to allow extra air into a set of air bleeds in the carburetor to lean out the fuel mixture.