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fuel system or evap? they are both near the intake, fuel is on the fuel rail going to the injectors and evap is on one of the vacuum lines that travel from the intake to the evap canister, it has a tag on it and a green cap.
The vacuum canister is up above the fuel tank (visible on driver side, forward corner of fuel tank.
The Evap canister (charcoal canister ) collects fuel vapour until it is drawn into the intake system when the evap solenoid is operated by the ECU
The canister stores gasoline vapors from the fuel tank so they can be ran into the engine and burned.
Not knowing what year the vehicle is and assuming you mean the "EVAP charcoal canister", if the vehicle has a carburetor, I would suspect the carb is flooding.
The Evaporative Emission Control System monitors the fuel vapor flow between the engine intake manifold and the EVAP canister. The system failure occurs when a leak or blockage between the intake manifold, the EVAP canister purge valve and the EVAP canister is detected by the PCM. Code P1443 Possible Causes: - Pinched, blocked or plugged fuel vapor tubes/hoses (except between fuel tank and EVAP canister) - Damaged EVAP canister - Disconnected, cracked or cut fuel vapor tubes/hoses (except between fuel tank and EVAP canister) - Damaged EVAP canister purge valve
It is not pressurized. A breather valve at the fuel tank allows fuel vapor to flow out of the tank and be stored in a charcoal canister until it is drawn into the intake of the engine. It also allows fresh air into the tank to prevent a vacuum. The fuel cap is not vented, all air moves through the breather valve. Technically it may, at times, be pressurized or have a vacuum. However, a properly functioning vapor system should limit that to a max of .725psi, or a vacuum of .45in. Hg.
Usually, it is not essential in the function of the engine. It serves more of an environmental protection purpose and has as slight use in improving fuel mileage. Without the canister, the fuel system can vent some fuel vapors directly to atmosphere (not very enviro-friendly and wasting fuel) instead of storing them for reintroduction into the fuel system.
any petcocks on the throttle body or intake are vacuum lines excluding fuel lines
on the top of the intake manifold next to the main injector
This indicates that a part of the EVAP control system is no longer fuctioning correctly. The EVAP system consists of many parts, including (but not limited to) the gas cap, fuel lines, carbon canister, purge valve, and other hoses. The (EVAP) emission control system prevents the escape of fuel vapors from a vehicle's fuel system. Fuel vapors are routed by hoses to a charcoal canister for storage. Later, when the engine is running a purge control valve opens allowing intake vacuum to siphon the fuel vapors into the engine.
on modern cars the fuel system is unvented. The evap purge and vent solenoid goes to a charcoal canister. When the vehicle is off the fuel tank is connected to the charcoal canister through the P/V solenoid and it absorbs the vented gas fumes from the tank. When the vehicle is on and at speed the solenoid switches and the charcoal canister is connected to engine vacuum and the vacuum of the engine purges the gas fumes in the charcoal through the engine burning them