Sylvie Willis
A fuel vapour line is a component of a fuel system, which is connected to a special outlet in the fuel pump. It allows vapour that forms in the fuel pump to return to the fuel tank. The vapour-return line also permits excess fuel being pumped by the fuel pump to return to the tank, which helps to keep the fuel pump cool. Fuel lines are made from steel tubing, which is wound with steel springs at certain points to protect against damage.
| Characteristics | Values |
|---|---|
| Purpose | To prevent fuel vapour from going into the atmosphere |
| Impact on car power | Does not rob car of power |
| Impact on fuel | Prevents fuel from being delivered to the engine |
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What You'll Learn
- The vapour-return line runs from the fuel pump or the fuel filter to the fuel tank
- Vapour-return lines can have an in-line check valve to prevent fuel from feeding back to the carburettor
- Vapour lines and hoses allow fuel to be supplied to the carburettor
- Vapour lines must be made of materials that can resist attack by fuel vapours
- Steel tubing is used for fuel lines that are fastened to the body, frame or engine
The vapour-return line runs from the fuel pump or the fuel filter to the fuel tank
The components of the fuel system are connected by fuel and vapour lines and hoses. These allow supplying fuel to the carburettor, to return excess fuel to the tank, and to carry fuel vapour. Fuel lines must be routed so as to remain as cool as possible. If any part of the line is accessible to much heat, the gasoline passing through it vapourises more rapidly than the fuel pump can create suction. Lower pressure or partial vacuum in the fuel pump also causes fuel to vaporise. This condition produces a vapour lock due to which the fuel pump delivers only vapour to the carburettor and also the vapour goes out the bowl vent without the engine receiving any gasoline.
All fuel lines which are fastened to the body, frame, or engine are of seamless steel tubing. Steel springs are also wound around the tubing at certain points to protect against damage. Wherever fuel line is replaced, only steel tubing should be used. Copper and aluminium tubing should not be substituted for steel tubing. These materials do not withstand normal vehicle vibration and may also react with gasoline chemically. Synthetic rubber hoses are used in most fuel systems where flexibility is needed. Connections between steel fuel lines and other components of the system are often made with short hose sections. The inside diameter of fuel delivery hose is generally larger (8 to 10 mm) and of the fuel return hose is smaller (6 mm). Materials of vapours vent lines must be capable of resisting attack by fuel vapours. A metal or plastic restrictor is mostly used in vent lines to control the rate of vapour flow. These are located either in the end of the vent pipe, or in the vapour-vent hose itself.
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Vapour-return lines can have an in-line check valve to prevent fuel from feeding back to the carburettor
Vapour-return lines are a type of fuel line that routes excess fuel from the engine back to the tank. They are connected to a special outlet in the fuel pump and can also be connected to a vapour separator, which consists of a sealed can, a filter screen, an inlet and outlet fitting, and a metering orifice, or outlet connecting to the fuel tank. Vapour-return lines are not present in most carburettors, but those that do have them can run fine without them because the electric pump is fairly weak.
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Vapour lines and hoses allow fuel to be supplied to the carburettor
Vapour lines and hoses are connected to a special outlet in the fuel pump. They allow excess fuel being pumped by the fuel pump to return to the tank. This excess fuel helps to keep the fuel pump cool. Vapour lines and hoses also carry fuel vapour.
It is important that fuel lines are routed so as to remain as cool as possible. If any part of the line is exposed to too much heat, the gasoline passing through it vapourises more rapidly than the fuel pump can create suction. Lower pressure or a partial vacuum in the fuel pump can also cause fuel to vaporise. This condition produces a vapour lock, which means the fuel pump delivers only vapour to the carburettor.
All fuel lines that are fastened to the body, frame, or engine are made from seamless steel tubing. Steel springs are also wound around the tubing at certain points to protect against damage. Steel tubing should be used whenever a fuel line is replaced. Copper and aluminium tubing should not be used as substitutes for steel tubing as these materials do not withstand normal vehicle vibration and may react with gasoline chemically.
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Vapour lines must be made of materials that can resist attack by fuel vapours
Vapour lines are an important part of fuel systems, connecting the components of the system and allowing excess fuel to return to the tank. They also carry fuel vapour and help keep the fuel pump cool.
Steel tubing is commonly used for fuel lines and is fastened to the body, frame, or engine. Steel springs are also wound around the tubing at certain points to protect against damage. Synthetic rubber hoses are used in most fuel systems where flexibility is needed, and connections between steel fuel lines and other components are often made with short hose sections.
It is important to note that copper and aluminium tubing should not be used as substitutes for steel tubing. This is because these materials do not withstand normal vehicle vibration and may also react chemically with gasoline.
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Steel tubing is used for fuel lines that are fastened to the body, frame or engine
Fuel vapour lines are connected to a special outlet in the fuel pump and allow vapour to return to the fuel tank. They also permit excess fuel being pumped by the fuel pump to return to the tank, which helps to keep the fuel pump cool.
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Frequently asked questions
A fuel vapour line is a component of a fuel system that allows vapour to return to the fuel tank.
A fuel vapour line allows vapour to return to the fuel tank, preventing vapour lock. Vapour lock occurs when the fuel pump delivers only vapour to the carburettor and the vapour goes out the bowl vent without the engine receiving any gasoline.
A vapour-return line is a type of fuel vapour line that runs from the fuel pump or fuel filter to the fuel tank. It is connected to a special outlet in the fuel pump and allows any vapour that forms in the fuel pump to return to the fuel tank.
The purpose of a vapour-return line is to allow excess fuel being pumped by the fuel pump to return to the tank. This excess fuel helps keep the fuel pump cool.
Fuel vapour lines are made of steel tubing. Steel springs are also wound around the tubing at certain points to protect against damage. Materials of vapour vent lines must be capable of resisting attack by fuel vapours.
