Engine Management Systems
Engine Management Systems
Business Division
Fuel Pumps 

Fuel Pumps

The main causes of fuel pump wear or failure is contamination of the fuel system, dirty/missing filter and/or corrosion due to moisture in the fuel. Fuel pump performance can be affected by particles as little as 10 Microns (0.01mm).

A worn/damaged fuel pump can cause:

  • Fuel pressure drop
  • Lean mixture
  • Rough idling
  • Poor performance
  • Spluttering at high engine rpm
  • Hard starting
  • Rough engine running
  • Excessive noise (usually associated with contaminated fuel)
  • High current draw
  • Fuel pressure fluctuations or surge

Replacement benefits, compared to a worn fuel pump:

  • Restore original system pressure
  • Restore engine power
  • Provide smoother running
  • Improve starting

Why choose a Bosch fuel pump?

  • Bosch is the leading supplier to OE manufacturers and is a leader in fuel pump technology
  • Bosch aftermarket fuel pumps all meet OE specifications
  • Broadest market coverage of any manufacturer with the right fit/quality and importantly competitive pricing

Bosch fuel pumps are competitively priced and sold through leading automotive part stockists. Please see our ‘Dealer Locator’ at the top of the page to locate you local store.

Purpose and Function.

Modern EFI fuel systems circulate as much as 200 litres per hour (~ 3 litres/min) of fuel at pressures between 2.5 – 3.5 bar (250 – 350 kpa).

Modern electric fuel pumps are “Positive Displacement” type pumps, this means that the pump cannot produce pressure unless it is acting upon a restriction. The only “restriction” in the system should be the fuel pressure regulator. The regulator controls the system pressure; the pressure ability or flow volume capacity of the fuel pump will not alter the system pressure.

Due to the high pressure and volume requirements placed upon these pumps, manufacturing tolerances are extremely fine. Motor speeds can be as high as 10,000 RPM and the clearances within the pumping elements down to microns. Cleanliness of the fuel system is vital, with an efficient high quality filter an essential part of the fuel system.

Specification Details.

Fuel pump specifications are given in relation to their engineering design specification. Hence the flow rates quoted are for the operating pressure and flow rate required to suit Original Equipment requirements. The specification guarantees the flow rate at the specified pressure or less. Whilst reduction of pressure will increase flow slightly, manufacturing tolerances between pumps differ and hence we do not specify exact flow rates at pressures other than those stated here.

Power Ratings of Fuel Pumps. [Horsepower]

It has become an aftermarket performance industry practice to rate fuel pumps in relation to expected engine power outputs, mainly Horsepower.

As this method of measurement has many issues in relation to various calculation methods, accuracy, individual interpretation and overall relevance, Bosch as an Original Equipment supplier of fuel pumps, does not subscribe to this specification method. 

The major design requirements of vehicle manufacturers of any type of pump is to provide a specified flow volume at a specified pressure, therefore manufacturing standard engineering measurements will only be used.

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