What’s an inline fuel pump?

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An inline fuel pump can be located inside the fuel tank or mounted along the frame of a vehicle. It is battery-powered and connected to the electrical system, and has an advantage over traditional fuel pumps in that it is less susceptible to heat-related vapor lock. It also pushes fuel from the rear-mounted fuel tank into the engine compartment, making it easier to transfer fuel. The electronically operated pump in-line model maintains fuel pressure and flow more consistently than an engine-driven pump.

An inline fuel pump can take different forms. One type found in most modern fuel-injected vehicles can be found inside the vehicle’s fuel tank. The fuel pump is actually located in the fuel tank and is connected to the fuel line inside the tank. Another type can be found mounted along the frame or chassis of a vehicle. This type of fuel line is often found on carbureted vehicles as well as high performance vehicles.

The difference between an inline fuel pump and a traditional fuel pump is that a traditional fuel pump connects to the engine block. This type of pump is usually ejected from the camshaft via an eccentric wheel. The wheel is attached to the camshaft in a material that allows it to operate in an oblong circle. As the fuel pump arm moves over the wheel, it makes a pumping motion as the wheel moves up and down. An inline fuel pump is usually battery powered and connected to the vehicle’s electrical system.

One advantage the inline fuel pump has over the traditional block mounted pump is the lack of heat related vapor lock. As fuel heats up, it may tend to vaporize. This causes a condition known as vapor lock, where the pump can no longer pump and move the fuel to the engine. By locating the fuel pump away from the engine and mounting it away from any heat sources, this condition is rarely a factor in pump performance. Most inline fuel pump systems use a return line to bleed excess fuel back to the fuel tank, thus relieving pressure and heat from the fuel pump.

By nature, most engine-mounted fuel pumps bring fuel from the rear of the vehicle into the engine compartment. The inline fuel pump pushes fuel from the rear-mounted fuel tank into the engine compartment. As with most mechanical operations, physics makes it much easier to push than to pull an object. Therefore, the rear-mounted fuel pump can operate with less effort to transfer fuel from the tank to the engine than an engine-mounted system.

With the electronically operated pump in-line model, it maintains fuel pressure and flow much more consistently than an engine-driven pump that is subject to variations in engine speed. The inline fuel pump also allows you to bleed the fuel system when the electrical system is turned on. The engine driven pump cannot pump fuel until the engine has been cranked and started.

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