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What is a Diesel Pump?

Patrick Roland
Patrick Roland

Diesel engines are considered some of the most powerful and reliable motors available, but their horsepower would be useless if it wasn't for a small component called the diesel pump. This little device helps get fuel from the tank to the engine in order to promote the combustion that allows automobiles to carry families and semi trucks to haul big loads. There are two kinds of fuel pumps, depending on the type of engine and the age of the vehicle. Malfunctioning fuel pumps can be the cause of many engine problems.

A diesel pump is the gate between the engine's fuel line and its carburetor. There are two distinct kinds of pumps, known as mechanical or "puller" pumps and fuel injection or "pusher" pumps. These are found in every engine that uses diesel fuel. Without it, there would be no regulation of the amount of fuel reaching the engine, and it could receive either too much or too little, resulting in a malfunctioning engine.

Diesel engines require a diesel pump.
Diesel engines require a diesel pump.

A mechanical puller diesel pump primarily is a rubber seal that opens and closes to allow fuel from the tank to enter the carburetor. Each time the cam shaft makes a rotation — most cam shafts make several per second — an attached arm raises and lowers. This arm is attached to an inlet valve that opens the seal for a fraction of a second. This welcomes fuel into the engine in order to aid combustion and power the motor. When this occurs, the combustion continually rotates the cam shaft, so, in essence, the mechanical diesel pump is self-propelled.

A fuel injection pusher diesel pump is a more modern way of ferrying fuel from the tank to the engine and is found in most high-performance cars and many newer vehicles. This pump is located within the fuel tank or near the fuel tank and is electronically controlled by the engine's computer system. The mechanical pump pulls fuel through using pressure, but the fuel injection system pushes fuel through the line toward the engine. This allows for an even more precise amount of fuel to flow and is the premier reason that it is the preferred method for high-performance vehicles.

Poor engine performance often can be traced to a fuel pump, no matter whether it is electric or mechanical. When bearings and seals wear down over time, the amount of fuel entering the engine is less precise and can contribute to engine failure. Dirt and rust often get past the filter system and clog up the small openings within a pump, also resulting in engine failure.

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    • Diesel engines require a diesel pump.
      By: Anna Lurye
      Diesel engines require a diesel pump.