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The function of a fuel transfer pump is to transfer fuel from a tank to a vehicle or from one location to another. Fuel transfer pumps have a variety of uses, such as fueling forklifts for large commercial vehicles such as buses or trucks, all the way up to large utility vehicles used on construction sites or in quarries.
In most modern vehicles, the fuel pump is usually part of a complete fuel pump assembly that includes the sending unit, horizontal arm and fuel filter.
Mechanical fuel pumps are used in vehicles with engines that use a carburetor as the device that delivers fuel to the engine. These are usually older vehicles. Newer vehicles will not have this type of fuel pump. Mechanical fuel pumps are located in the engine compartment.
Electric fuel pumps are the most common type of fuel pump found in vehicles on the road today. In most cases, you will find the electric fuel pump submerged directly into the fuel tank, working in conjunction with the injectors in the vehicle. Electric fuel pumps typically pump gas at a higher pressure than mechanical fuel pumps (typically around 30-40 psi compared to the older mechanical fuel pumps that typically pump 2-6 psi).
Another type of fuel pump that can be found on direct injection vehicles is the direct injection fuel pump. A direct injection fuel pump combines elements of a mechanical fuel pump and works in conjunction with an in-tank electric fuel pump. Direct injection fuel pumps are usually located in the engine compartment and are mechanically driven by a camshaft, oil pump or vacuum pump. The in-tank electric fuel pump delivers fuel from the fuel tank to the direct injection fuel pump at a typical fuel pressure of 35-40 psi. The direct injection fuel pump then increases the pressure to about 2000 - 3000 psi and injects it directly into the combustion chamber.
The fuel pump in your vehicle pushes fuel from the fuel tank to the engine. The unit is usually mounted in the vehicle's fuel tank using an electric motor and consists of a series of valves and springs that work in tandem to create suction. This suction draws fuel into the pump, which causes the reset spring to push the fuel upward into the line, creating pressure.
The fuel pressure in the line is not regulated by the pump itself; the pump will only use the voltage provided by the vehicle to pump to its maximum capacity. Fuel pressure is regulated down the engine fuel line by a fuel pressure regulator (also known as an FPR). The higher the voltage applied to the pump, the faster the pump moves and the greater the fuel flow from the pump. Typically, the fuel pump is part of an assembly that also includes the sending unit, horizontal arm and screen filter.
The first sign may be the sound. It is normal for the fuel pump to make a low humming sound that you may hear coming from the fuel tank area. As the pump begins to wear out, this sound will turn into more of a whine or buzz.
Once a failure occurs, you may notice signs that the pump is running at a lower efficiency. You may not be able to start the engine. You may have to hold the ignition longer than usual before you get enough fuel, or you may have to make several attempts to get the engine started.
If the engine is low on fuel, it will sputter, cough, and occasionally stall. Running low on fuel can cause the engine to misfire.
You may also feel a difference in performance, with weaker acceleration and poor fuel economy.
You may also experience sudden power surges. This can happen when the pump's performance is erratic, meaning it sometimes increases the amount of fuel it uses to push the engine, and sometimes decreases it.
Once the fuel pump stops working, you won't be able to start your car.
The most effective option for testing for fuel pump failure is to connect a fuel pressure gauge to the common fuel rail of a fuel injected engine. The store manual or vehicle service manual will provide fuel pressure specifications at various RPM rates with tolerance ranges. If the measured fuel pressure is not within these parameters, the pump may be defective. Testing the pressure in the line between the fuel pump and the fuel pressure regulator will confirm a faulty pump or indicate a faulty regulator.
If the vehicle will not start at all, but the engine will crank (turn over and not start) when the key is turned, the problem may be fuel delivery. Again, testing the fuel pressure will determine if this is the case. Another simple test is to turn the key to the "on" position without starting the vehicle and listen to the fuel pump. The electric fuel pump will make a quiet whining sound when first started, which can be heard from outside the vehicle.
Diagnosis can be tricky if your car's engine sputters or stalls after running without problems for a while. This usually happens when the engine has been running at cruising speed for a while and then slows down at a stop light or stop sign. In this case, the engine may be failing for more reasons than we can list.
However, if you have a sputtering engine and a "lean mixture" check engine code, it may indicate a problem with the fuel pump. The diagnostic procedure here is to bring the engine up to temperature and then perform a fuel pressure check.
Fuel pumps come in different shapes and sizes, and have different functions. For unmodified stock vehicles, choosing a fuel pump is simple. Simply select a pump based on your vehicle's VIN, pump OEM number or your vehicle's make, model and year. When looking for a fuel pump with a modified or custom fuel delivery unit for a performance engine, it is important to make sure they choose the right one for their engine. Different factors can influence the choice of fuel pump. However, the most important determinants include the engine's fuel efficiency, horsepower, voltage and maximum fuel system pressure.
The efficiency of an engine is the amount of fuel required to produce 1 HP in 60 minutes. It is also known as the engine's brake specific fuel consumption (or BSFC for short).
The fuel quantity of a vehicle depends on its horsepower rating and BSFC, and the owner can calculate the average fuel requirement by multiplying these two values together. For example, for a 650 HP engine with a 0.45 BSFC, the fuel requirement is equal to 660 times 0.45, or 292 pounds of fuel. The higher the efficiency of the engine, the higher the BSFC and the amount of fuel required. When purchasing an electric fuel pump, it is best to err on the side of caution and purchase a pump that can deliver slightly more fuel than the engine actually needs. Drivers unsure of their car's horsepower should consult an experienced mechanic. Calculations based on incorrect HP estimates can result in serious engine damage.
Modern electric fuel pump systems rely on electricity. Fuel injectors are designed to operate within specific voltage limits. When selecting a fuel pump, the driver must select a pump that is appropriate for the voltage output of the engine. For example, connecting a fuel pump designed for 12 volts to another vehicle with an output of 13.5 volts can increase the amount of fuel pumped by up to 40%. This can quickly lead to pump problems. High voltages can also affect the fuel pump relay.
The flow rate of your fuel transfer pump should be determined by the size of the tank you are filling, as you need to control the speed. If the fuel moves too fast from the tank to the vehicle, it may overflow or froth, causing the automatic nozzle to shut off prematurely. To help determine the right flow rate for you, follow our simple guidelines.
Low speed (50 liters per minute), this is the recommended speed for smaller vehicles such as cars, vans, forklifts and small factory vehicles.
Medium speed (70 liters per minute), which is the recommended speed for larger vehicles, such as large vans, rigid trucks, farm vehicles and small public service vehicles.
High speed (90 liters per minute), this is the recommended speed for fuel pumps that will be used for large capacity tanks, such as buses, coaches, articulated vehicles and heavy equipment, quarry and mining vehicles.
Replacing a faulty fuel pump is not a simple task. It involves dropping the fuel tank, removing and replacing the fuel pump assembly, and then testing all the work. The fuel pump should also be replaced along with the fuel filter and the pump connectors (on both sides of the plug) should be checked to make sure they are not burned or overworked.
When you purchase a fuel pump, we offer free online and phone technical support. Please visit our catalog page to see what fuel pump options we have for your vehicle.
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