Fuel Delivery and Air Induction: Description and Operation

GENERAL DESCRIPTION
The fuel supply and air induction system is used to deliver the air/fuel misture to the combustion chamber.

The Fuel System consists of three major sub-systems:
^ The fuel storage system,
^ Feedback controlled carburetor, and
^ The fuel delivery and return system.

FUEL STORAGE
The fuel storage system consists of a fuel tank, fill spout and filler cap.

FEEDBACK CONTROLLED CARBURETOR
The carburteor is a two-barrel down draft type. It consists of the following systems:
1. Fuel resovoir system;
Float
Return circuit
2. Primary circuit;
Slow system
Main system
Accelerator pump system
Choke system
3. Secondary circuit;
Step system
Main system
4. Coasting fuel cut system
5. Automatic choke system

For a more detailed description of the feedback control system operation, refer to Computers and Control Systems.

FUEL DELIVERY AND RETURN
The fuel delivery system delivers fuel at a pressure and quantity high enough to maintain fuel in the carburetor under all driving conditions.

The fuel delivery components consist of fuel supply lines, a plunger-type fuel pump and a fuel filter assembly.

The fuel return system recovers excess fuel from the carburetor and returns it to the fuel tank. The fuel return line is low pressure and returns directly to the fuel tank. The fuel return system consist of lines and couplings

FUEL VAPOR RECOVERY
The fuel vapor recovery system provides a route for the recovery of fuel vapors (from the fuel tank and float chamber) either for storage in the charcoal canister, or for evacuation through the purge control system. The vapor recovery system also consists of lines and couplings. Additionally contained in the vapor recovery system are two components, an overfill limiter and a fuel check valve. These components function as evaporative emissions control devices and are covered in detail in Emission Control Systems.