How to Shop for Car Fuel Pumps on eBay

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How to Shop for Car Fuel Pumps on eBay

Most modern cars these days have a Zen-like, minimalist build, but under its hood and inside its frame are complicated parts that work together to make the car function. Among the many components of a car are the air intake and fuel delivery parts. Assembled and connected together, they control the flow of air and fuel within the car. On the fuel's route to the engine, the first point of action happens in the car fuel pump. There was a time when car fuel pumps were not part of a car, but now only a limited number of cars do not need a car fuel pump. These car models that require only gravity to feed fuel are dwindling in number.

Most cars today need help from the fuel pump to direct petrol or diesel to the intake valve or chamber. There are two types of car fuel pumps, and the difference between them is important knowledge for someone shopping for a replacement fuel pump. In addition, there are a wide variety of manufacturers that make fuel pumps for different brands, so choosing the right one among them would be easier with knowledge about car fuel pumps.

Car Fuel Pumps

When it comes to fuel feeding, there are two types of cars. One is the gravity feed design, and the other is the non-gravity feed design. A car with gravity feed design has a tank placed higher than the engine so fuel travels to the engine with the help of gravity only. In contrast, a car with non-gravity feed design needs a fuel pump to deliver fuel engine, especially useful when accelerating hard and driving uphill. Cars can have a mechanical or electrical fuel pump. Choosing between the two on eBay depends on the set-up of the engine of the parts, particularly the existence or nonexistence of certain parts.

Mechanical Fuel Pumps

Mechanical fuel pumps came before their electrical counterpart. They are also referred to as diaphragm pumps. A non-gravity fuel pump is located on the engine block or the head of the cylinder, and a camshaft controls it by forcing the pump's lever up and down. Carburetted car engines use mechanical fuel pumps to direct fuel from the fuel tank to the fuel bowl of the carburettor.

As the camshaft clicks the lever, the lever in turn pushes a spring that sets other springs in motion until the diaphragm is pushed down the bowl of the pump, increasing the level of fuel in the pump's own fuel bowl. The pressure of the diaphragm forces the fuel up and out of the pump through an outlet. The fuel then gushes into the carburettor. There is a check valve at both the inlet and outlet parts to make sure that the flow of the fuel is unidirectional. A mechanical fuel pump operates at a pressure from 4 to 6 pounds per square inch.

When to Replace a Mechanical Fuel Pump?

There comes a point when a mechanical fuel pump replacement is necessary. A leak in its diaphragm can cause the engine to stall, misfire, or hesitate. A mechanical fuel pump that has failed does not deliver fuel to the carburettor, so the engine is unable to start or run.

To check if the mechanical fuel pump is working properly, look at the throat of the carburettor and pump the throttle linkage. You should see that fuel is squirted into the carburettor. Otherwise, it means that the pump is not working. If fuel drips from the pump, it means that the diaphragm of the pump has failed. This warrants fuel pump replacement because a leaky fuel pump can cause fuel to ignite and start a fire.

Electrical Car Fuel Pump

This type of fuel pump is present in modern cars. An electric car fuel pump operates at a pressure of 30 to 40 pounds per square inch. There are two subtypes of electrical fuel pump: the in-tank fuel pump and the in-line fuel pump.

In-Tank Fuel Pump

As it name suggests, an in-tank fuel pump is located inside a pump. Putting a pump inside the tank makes the tank less likely to handle gasoline vapour farthest from the engine. Also, it is less likely to start a fire. This type of fuel pump provides a constant flow of fuel to the engine, and fuel not used returns to the tank. The pump generates positive pressure in the fuel lines to push fuel to the engine. In an event of collision, cars with fuel injection is equipped with an electronic control unit that shuts off the electronic fuel pump to prevent the leaking of fuel from the pump.

In-Line Fuel Pump

An in-line car fuel pump is linked to the fuel line while being wired to the battery. This variety of electric car fuel pump, which is tubular in construction, contains several pumping systems. During the transfer of fuel from the tank to the engine, the fuel from the tank is sucked inside the pump, particularly in the fuel feed pump. If there is residue in the fuel, a mesh screen filters it before sending the fuel to the metering pump.

The metering pump then pushes, pulls, spins, and jostles the fuel to generate high pressure. The process thins and separates the fuel to make sure it meets specific standards before being pumped out into the fuel rail through the fuel line. From there the fuel is sprayed as a fine mist into the intake chamber of the cylinder with a tiny nozzle. Technology allows an in-line fuel pump to be placed outside the tank without the risk of ignition.

When to Replace an Electric Fuel Pump?

Electric fuel pumps can also fail. If an engine does not start or if the car stalls or jerks while on the road, a faulty electric fuel pump is usually the cause. When the engine is turned on, hearing a whirring or humming sound signifies that the electric fuel pump is starting. When there is no noise, there could be a problem with the fuel pump.

Differences Between a Mechanical and an Electrical Fuel Pump

The table below shows the major differences between a mechanical and an electric fuel pump. Their differences include placement in the car, pressure, pressure output difference, and fuel transfer location.

Fuel Pump Type



Pressure Output Difference


On or near the engine

Operates at 4 and 6 pounds per square inch (psi)

Usually for cars having carburettors


Anywhere but works best when near or inside the fuel tank

Capable of operating at 30 to 40 pounds per square inch (psi)

For cars having fuel injection system

The table above can be a quick reference guide for car owners. As a rule of thumb, electric car fuel pumps are used more often in modern cars.

What to Look for in a Car Fuel Pump

Before purchasing a car fuel pump there are factors that buyers need to consider. These factors include the volume-pressure ratio, flow, and voltage.

Volume-Pressure Ratio

Regardless of whether a car fuel pump is mechanical or electric, it can be an HVLP or HVHP pump based on the volume-pressure ratio. HVLP is a high volume, low pressure pump that transfers a high volume of fuel while under very low pressure conditions. HVHP is a high volume, high pressure pump that operates at a very high pressure to provide the same volume as an HVLP pump. Usually in fuel pumps, as the pressure increases, the flow of fuel decreases. For this reason, HVHP pumps are preferred because this type of pump allows fuel to flow at a high level even in high-pressure situations.

Flow and Voltage

A fuel pump might claim that it pushes out a volume of 255 litres per hour (lph), but it is important to consider not only the volume of fuel the pump can push out per hour but also the amount of pressure in pound per inch it has at that particular volume. This is because when the pressure increases, the volume or the flow of fuel decreases.

For instance, Pump A is rated at 255 lph at 40 psi, and Pump B is rated at 255 lph at 50 psi. Pump A and B seem to offer the same flow, but due to pressure-volume relationship, Pump A could possibly yield 210 lph only at 50 psi, which is 40 litres less than Pump B. The voltage of the pump also affects the flow of the fuel. The higher the voltage, the more fuel a pump can push out. For instance, in 12 volts a Brand X Pump rates at 255 lph at 40 psi, but when run on 14 volts, Brand X Pump pushes out more fuel, specifically 300 lph at 40 psi.


Car fuel pumps can be categorised into two types: mechanical and electrical car fuel pumps. A mechanical fuel pump has the characteristic lever as well as diaphragm set up, and fuel flows out of the pump by the downward pressure of a diaphragm. An electric car fuel pump, which is tubular in construction, creates a positive pressure to get the fuel from point A to point B. Electric car fuel pumps can further be categorised into two: in-line and in-tank. As their names suggest, the subtypes of the electric car fuel are placed differently in a car.

When looking for the right car fuel pump, buyers must check not only the volume but also the pressure. Even if pumps rated at 255 lph at 40 psi, and 255 lph at 50 psi seem to offer the same flow, the one with 50 psi still provides better flow since it holds true that as the pressure increases the flow of fuel decreases. Increasing the voltage to a fuel pump increases the amount of fuel a pump pushes out. The pump is the catalyst that sets the fuel running, and choosing the right one contributes a great deal to the performance efficiency of an engine. To choose the right car fuel pump, determine first the pressure output difference of the car, and then check the volume, flow, and voltage of the car fuel pump. Taking the aforementioned factors into consideration ensures a quick shopping experience on eBay for fuel pumps.

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