Quick Answer: Why do carburetors have 2 lines?

What are the two hoses on a carburetor?

Like you said the petcock has two tubes; one is a vacuum and the other is the fuel feed to the carbs.

Which fuel line goes to the primer bulb?

The (clear) fuel intake line runs from the top of the carburetor (straight nipple) and goes to the short post on the back of the primer bulb. The return line (blue) comes from the long post on the back of the primer bulb and goes into the bottom of the fuel tank.

Do carbs need a return line?

Registered. Yes, depends on the setup….. most aftermarket regulators have a return port in them. If you run a return your pump will run cooler and run for longer.

Why do I need a fuel return line?

It’s primary purpose is to return excess fuel from the carburetor to the fuel pump, however it serves other important functions as well. Aside from providing a path for excess fuel to return to the tank, the fuel return hose also prevents vapor lock and over pressurization from occurring within the carburetor.

What are the three hoses on a carburetor?

One is the bowl drain, and the other is a overflow drain. And the other is your fuel inlet.

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Should a primer bulb have gas in it?

You should have fuel in the bulb when running. If you do not, the check valve in the primer is bad. It is essentially not seating and drawing air in through the discharge port. Then there is the other style that is a little more complex but works on the same principle as the Purge Primer.

What size fuel line should I use?

Recommended Size, Based on Horsepower

Recommended Fuel Line Size (from the tank to the pump)
Engine Output Size (inches) Size (AN)
350 hp or less 5/16 in. -5
350-450 hp 3/8 in. -6
450-650 hp 1/2 in. -8

Can you block off fuel return line?

Any fuel going through the return line is simply fuel your engine did not need/could not use. Blocking or restricting the line only increases fuel pressure at the injectors. Blocking the line results in the fuel pressure just being the maximum the pump can push.

What Is a Dead Head fuel system?

Return or dead head? The term “dead head” simply means that the fuel in the system does not recirculate back to the gas tank from the front of the car. A return system recycles fuel back to the tank using either a bypass at the fuel pump or at the regulator.