The fuel delivery system of a vehicle consists of two components, the lift pump and the fuel pump. The lift pump works mostly at low pressure, usually around 5-10 psi, and solely exists to pull fuel out of the tank for the main fuel pump. It has a flow of 50- 100 litres per hour and feeds the main pump to ensure that it gets an even supply of fuel from its source.
A fuel pump, on the other hand, which is also known as high-pressure fuel pump delivers at quite higher pressures; normally between 40 and 80 psi. This pump has to ensure maximum fuel flow with the right pressure delivered directly to the engine for perfect combustion. Fuel pumps have an efficiency of more than 90 percent again according to a report from the Fuel Pump Manufacturers Association, and lift pumps are slightly lower at around 80 percent due to their simpler design.
Automotive engineer Robert Johnson emphasises this idea: “Being familiar with the function of each pump in your fuel system is critical to make sure your vehicle operates as it should.” The question that was posed was very simple: What makes a lift pump different from a fuel pump? What could the correct answer possibly be, do you know the confusion here is; lift pump helps in moving of fuel towards the main pump and as for fueling of engine with a proper pressure and flow rate we need fuel pump.
We can observe an application of this in practice, for instance, as diesel engines generally use both pumps. The lift pump is what carries fuel from the tank up to the fuel pump which then pressurizes the fuel that gets sent to injectors. A diesel lift pump might be rated at something like 30 liters per hour, while the fuel pump could top 200 liters per hour: Both need to work in harmony.
While the cost of lift pumps usually falls between $50 and $150, many high-pressure fuel pumps are priced from around $100 to as much as $500. Lift pumps will generally last on average between 50,000 to 100,000 miles while fuel pumps can be expected to last anywhere from 60,000 t0 120,000 miles necessitating regular maintenance to ensure the long-term reliability of your vehicle.
For additional information on overall performance fuel pumps, click Fuel Pump.