Electric fuel pumps E1F, E2T and E3T - blocked prefilter

Pierburg | Motorservice

Fuel pumps from the model ranges E1F, E2T and E3T have a prefilter. What should be done when the fuel pump gets hot, makes loud noises or doesn’t generate enough pressure? Can the prefilter be cleaned if it gets blocked? And can the fuel pump also be run with diesel? Find the answers here.

Product: Electrical fuel pumps

Pierburg no.


7.21287.53.0; 7.21565.70.0/.71.0;


Most modern fuel pumps are flushed through with fuel, which lubricates and cools them. If this does not happen to a sufficient extent, e.g. through soiling, there is a risk of “dry running”. Fuel pumps in the E1F, E2T and E3T series are equipped with a built-in prefilter on the intake side. This small prefilter provides protection against contamination. It can become blocked due to dirt in the intake air.


  • fuel pump does not generate sufficient pressure and shows insufficient delivery rate
  • reduction in the delivery rate, through to blocking of the fuel pump
  • dry running of the pump leads to failure
  • damage to the fuel system
  • damage to the fuel injection system
  • fuel pump makes excessive operating noise
  • fuel pump heats up significantly
  • engine misfires
  • premature failure with just a low mileage
Prefilter of the E1F: new on the left, blocked on the right
Prefilter of the E3T – blocked by rust


In addition to water, impurities are the most common causes for this damage. Possible causes include:

  • rust formation in the fuel system due to condensate
  • intake of dirt in the fuel tank from outside (e.g. on refuelling)
  • ageing of the fuel due to longer periods at standstill (formation of deposits)
  • maintenance intervals (filter replacement) not complied with
  • poor fuel quality
  • old, porous fuel hoses


  • Flush the entire fuel system through with clean, quality fuel.
  • Clean the blocked separator on the intake side (the separator is not available as a spare part).
  • If necessary, replace the damaged fuel pump. Depending on the degree of soiling, it may be necessary to clean the entire fuel system (e.g. remove and clean the fuel tank too).


  • Pull the prefilter carefully out of the intake connection with tweezers. Attention: Do not damage the intake connection!
  • Clean the prefilter in fuel. Attention: Observe the safety regulations concerning the handling of fuel!
  • Plug the prefilter carefully into the intake connection again. Attention: Do not damage the intake connection!


Observe the following when retrofitting with an electric fuel pump type E1F: For petrol operation, the prefilter can remain in the pump.

For operation on diesel the prefilter must be removed, as problems may occur at low temperatures due to the higher viscosity of diesel.


For type E1F fuel pumps, Pierburg offers a fuel sieve filter (Reference number 4.00030.80.0) that reliably protects the fuel pump from dirt and other foreign particles, preventing premature failure. The sieve filter should be replaced at the same maintenance intervals as the fuel filter.

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