A Model A carburetors fuel supply must be clean and unrestricted. There are many potential contributors to dirty or restricted fuel.
Fuel Supply Must Be Clean
- Gasoline is contaminated before it is even put into the Model A tank
- Gas cap is rusty and drops particles into gas tank.
- Gas tank filter screen (also called spark arrestor) is rusty or dirty.
- Gas gauge mechanism is dirty, or more likely gauge cork is disintegrating.
- Gas tank contains rust, sludge, dirt, etc.
- Gas shut off valve is defective or is simply not open all the way.
- Gas shut off valve screen or micro filter is dirty or clogged.
- Fuel lines are dirty or clogged.
- Gas sediment bowl, screen, or filter contains too much rust, dirt, or sludge.
- Add on fuel filters can not only become restricted with dirt, rust, or sludge, but their basic designs are often a problem in that most are designed for fuel flow under pressure from a fuel pump.
- Fuel line is sticking out too far beyond fitting ferrule. (This can allow fuel line to bottom out against carburetor filter strainer.)
- Carburetor filter strainer is restricting flow.
- No matter how well a carburetor has been restored, if fuel supply is dirty or restricted the carburetor will soon not function properly.