In car fuel system what is difference between Fuel Feed pump and fuel pump

In a car's fuel system, both the fuel feed pump and the fuel pump are components that help deliver fuel to the engine, but they serve slightly different roles depending on the system design. Let’s break down the differences:

1. Fuel Feed Pump

Purpose:

• The fuel feed pump is responsible for drawing fuel from the fuel tank and supplying it to the primary fuel pump or directly to the fuel injection system, depending on the engine design.
• It ensures a steady flow of fuel to the main pump or engine.

Location:

• Usually located near the fuel tank or along the fuel line.

Commonly Found In:

• Older vehicles or systems with carburetors or mechanical fuel injection.
• Some diesel engines use a low-pressure fuel feed pump to transfer fuel to the high-pressure pump.

Pressure and Functionality:

• Operates at a low pressure (enough to transfer fuel to the main pump).
• Doesn't generate the high pressure needed for fuel injection.

 

2. Fuel Pump

Purpose:

• The fuel pump is the primary pump that pressurizes the fuel and sends it to the engine's fuel injection system or carburetor at the required pressure for combustion.
• It ensures the engine receives fuel at a pressure and flow rate optimized for performance.

Location:

• Can be located inside the fuel tank (in-tank fuel pump) or mounted outside the tank (in-line fuel pump).

Commonly Found In:

• Modern vehicles with electronic fuel injection (EFI) systems, as they require higher fuel pressures.
• Acts as both a feed pump and pressurizing pump in most modern gasoline engines.

Pressure and Functionality:

• Operates at high pressure to meet the demands of fuel injectors (e.g., 40–60 psi for gasoline engines, much higher for diesel common rail systems).

 

Key Differences

Aspect	Fuel Feed Pump	Fuel Pump
Function	Transfers fuel to the main pump or engine	Pressurizes fuel for injection or combustion
Pressure	Low pressure	High pressure
Usage	Common in older systems or diesel engines	Standard in modern fuel-injected engines
Location	Near the tank or fuel line	Inside or outside the fuel tank

 

Example in Diesel Systems

• Fuel Feed Pump: Transfers diesel fuel from the tank to the high-pressure pump.
• Fuel Pump (High-Pressure Pump): Pressurizes the diesel fuel to extremely high pressures (e.g., 25,000 psi) for injection into the engine.

 

Modern Systems

In modern cars, the fuel pump typically acts as a combined unit, performing both the feed and pressurization functions. However, in some advanced systems (especially in diesel engines), the separation of roles persists for efficiency and system complexity reasons.