There are many types of fuel pumps: mechanical, electric and high pressure and other fuel pumps. Fuel pump assembly can be used in cars, lawn mowers, golf carts, all kinds of machines. Knowing your fuel pump type and how it works can help you reduce the fuel pump replacement cost.

1. What Is A Fuel Pump

The fuel pump is the core component of the fuel pump assembly, and its main function is to suck fuel out of the fuel tank and deliver it to the fuel line. The fuel pump assembly can be mainly used in cars, lawnmowers, golf carts, motorcycles, auto zones ,boats, and all kinds of machines.

The fuel pump consists of an electric motor, a pressure limiter, and a check valve. The electric motor actually works in the fuel inside the pump housing because there is nothing inside the housing that can be ignited. The fuel lubricates and cools the fuel motor, and there is a check valve at the outlet. The pressure limiter is located on the pressure side of the fuel pump housing with a passage to the inlet. It is driven by the high-pressure pump shaft or engine. In some systems, an electrically driven pump is used to create an auxiliary pump.

2. Types of Fuel Pumps

There are many types of fuel pumps, which can be divided into the following main types: fuel transfer pump, high-pressure fuel pump, low-pressure fuel pump, mechanical fuel pump and electrical fuel pump. Their characteristics are quite different.

2.1 Fuel Transfer Pump

The fuel transfer pump is to transport lubricant oil which does not contain solid particles and fibers, is non-corrosive, temperature not higher than 80℃ and has a viscosity of 5×10-6～1.5×10-3m2/s(5-1500cSt), it is generally used in the hydraulic transmission system.

Fuel transfer pump application range: in the oil delivery system can be used as a transmission, or booster pump; in the fuel system can be used as a fuel pump for transmission, pressurization, and injection; in the hydraulic transmission system can be used as a hydraulic pump to provide hydraulic power; in all industrial fields, can be used as a lubricant pump.

2.2 High-Pressure Fuel Pump vs. Low-Pressure Fuel Pump

The role of the high-pressure fuel pump is to increase the fuel pressure high-pressure injection to achieve the atomization effect, high pressure oil pump is mainly used as a power source for hydraulic devices such as jacks, headers, extruders, and tying machines. While the low-pressure fuel pump is to supply the oil in the tank to the high-pressure oil rail.

2.3 Mechanical Fuel Pump vs. Electrical Fuel Pump

   Unlike mechanical fuel pumps, the injection timing and volume of electric fuel systems are electronically controlled and do not require manual adjustment. Consequently, electrical fuel pumps offer certain advantages over mechanical fuel pumps.

In addition, according to the voltage distinction, fuel pumps can be divided into three main categories:6-volt fuel pump, 12V fuel pump, , 24V fuel pump. It is worth noting that the voltage of an automobile gasoline pump is generally 12V.

3. What does a Fuel Pump Do
The working principles of different types of fuel pumps differ greatly, especially mechanical fuel pumps and electrical fuel pumps, and there are huge distinctions in how they work.

A mechanical fuel pump is driven by a camshaft or a special shaft driven by a crankshaft. As the shaft turns, a cam passes under a rotating lever and forces it to move upward at one end. The other end of the lever is loosely connected to a rubber diaphragm that forms the base of the pump chamber, and it pulls the diaphragm downward. As the lever pulls down on the diaphragm, it creates suction that draws fuel along the fuel line through the check valve into the pump. As the rotary cam is turned further so that it is no longer pressed against the lever, the lever moves backward through the return spring, thereby relaxing its pull on the diaphragm. The loosely connected lever does not push upward on the diaphragm, but there is a return spring that pushes on the diaphragm. The diaphragm can only move upward if the gasoline is removed from the chamber. Gasoline cannot flow back through the first check valve, so it flows out through another check valve that leads to the carburetor.

However, an electrical fuel pump has a similar diaphragm and valve arrangement, but instead of a camshaft, a solenoid valve (electromagnetic switch) provides the pull on the diaphragm. The solenoid attracts an iron bar that pulls the diaphragm down and draws gasoline into the chamber. At the end of its travel, the iron bar separates a set of contacts, cutting off the current to the solenoid and relaxing the pull on the diaphragm. As the diaphragm return spring lifts the diaphragm, it also pulls the rod away from the contacts; the contacts then close so that the solenoid pulls the rod and diaphragm down again.

4. How to Know If Fuel Pump Is Bad

Some parts of the car problems will produce different symptoms, the owner can determine through these signs of a bad fuel pump which part of the failure. But what are the specific signs of failing fuel pumps that can accurately determine that the fuel pump has been damaged? 

The main symptoms of a failed car fuel pump are the following:

1、The supply system of fuel collapses and the vehicle cannot be started.

2、Lower fuel supply pressure and no sound of the gasoline pump running.

3、Weak acceleration, there will be a strange noise when driving.

4、The engine fault light is on, and the engine shakes abnormally.

5、Difficult to start when starting, need to hit the key for a long time.

Once any of the above bad fuel pump symptoms occur, you need to be alert and watch out for a damaged fuel pump.

5. How Much Does It Cost to Replace A Fuel Pump

Under normal circumstances, the fuel pump is not a wearable part, but if it is not frequently refueled on time, then the fuel pump will be damaged. Fortunately, fuel pump replacement costs are not high compared to other auto parts.

There is a big difference in the cost to replace a fuel pump for different brands of cars. Generally, the higher the grade, the higher the replacement price will be, to Mercedes-Benz A-class, for example, its original fuel pump in China 4S store replacement prices of about 5,000-6,000 yuan, repair store replacement price of about 4,000-5,000 yuan.

6. How to Change A Fuel Pump
Generally, the fuel pump that we can replace by ourselves is mainly the automotive fuel pump. And the replacement of car fuel pump is divided into the following processes.

Step 1: Find the location of the fuel pump. The fuel pump can be located inside the fuel tank itself, outside the fuel tank, or inside the engine compartment. Remove the fuel pump and fuel lines. Inspect and clean the surrounding area, making sure to remove any contaminants.

Step 2: Open the engine end of the fuel line and blow out any foreign material in the fuel line. Install a new fuel pump and fuel filter, and reconnect the fuel line.

Step 3: Fill the fuel tank with uncontaminated fuel. You can use a fuel pressure tester to ensure that the fuel pressure and flow are within the required specifications.

Step 4: Remove all test equipment used and double-check all relevant connections and fittings for any possible leaks.

7. Common problems after changing fuel pump
There will still be a series of problems after the fuel pump of the car is replaced.

1、When the pump core is damaged, there is no sound of the gasoline pump operation when the key door is opened while the fuel supply system is working.

2、When the pump body is damaged, the engine cannot be started because the pressure relief and fuel pressure cannot reach the specified fuel pressure value and cannot be atomized well.

3, the gasoline pump is to rely on gasoline to conduct heat to cool down, the gasoline level is too low, and can not play a cooling effect, reducing the service life, so do not wait until the gasoline light alarm is still not refueled.

Conclusion:
The fuel pump is considered to be an essential part of the fuel system. The fuel pumps can be divided into several different categories based on different operating principles, with electric fuel pumps being the most commonly used. Besides, the fuel pumps used in different kinds of motor vehicles including cars and motorcycles are different. Despite the fact that the fuel pump is not easily damaged, it is worth noting how it breaks down in daily use. Especially when there is a frequent lack of oil, the fuel pump is likely to have been damaged and it's indispensable to have a replacement.