Installation errors with electric fuel pumps

Avoid mechanical damage, tightening without counter-tightening, contact corrosion

Information on diagnostics

Improper mounting or repair of a diesel or petrol pump can result in damage to components or materials. This can manifest in corrosion or wear. When tightening the connecting line, make sure that a nut is fitted to the relevant screw. If no lock nut is used, this can lead to defects and leakage on the pump, resulting in an increased risk of fire in the vehicle. As with all parts used in the engine, also make sure that no bimetallic corrosion occurs when connecting different metals – this can occur on screw connections or threads, for example. You can find further information on installation errors with fuel pumps in this article.

Inexpert installation or removal of a fuel pump can result in damages to the seal, housing or to electrical or fuel connections.

Tightening without counter-tightening
In type E2T and E3T toothed ring pumps, the mating component is often not countertightened against the pump housing when the fuel connecting line is tightened. This causes the entire pump cover to turn together with the connections in the housing. Consequently, the sealing ring beneath the cover is squashed. The twisting of the pump system often displaces or damages the O-ring that seals the housing from the cover. The pump then leaks from the flanged edge.

Note:
When the connecting line is tightened, the lower hex nut of the fuel pump must be counter-tightened, as otherwise leaks can occur in the fuel pump.

Attention:
Leaky fuel pumps increase the risk of fire!

Contact corrosion
Incorrect installation or retrofitting can entail the use of material combinations that encourage contact corrosion. For example, the pump housing (aluminium) should not come into contact with galvanised surfaces.

If zinc-coated steel clips without insulation are fitted directly to the aluminium body of the pump, for instance, and electrolyte (splash water) is present, contact corrosion may be produced. In the worst case, the pump body can leak due to pitting corrosion.

Attention:
Leaky fuel pumps increase the risk of fire!