Damage through contamination
The most common cause of malfunctions in the fuel system or premature failure of fuel pumps is contamination by larger or smaller particles.
The effects of contamination are varied:
Here are some possible causes:
The effects of contamination are varied:
- Clogged filters
- Reduced flow rate
- Fuel pump is excessively noisy
- Pump runs dry
- Jammed pump system
Here are some possible causes:
- Rust or chalk particles
- Dirt entering the fuel tank from outside (e.g. on refuelling)
- Ageing of the fuel due to longer periods at standstill (build-up of deposits)
- Maintenance intervals (filter replacement) not complied with
- Poor fuel quality
- Old, porous fuel hoses
- Entry of dirt and water through a scuffed tank ventilation hose, or due to incorrect subsequent rerouting of the tank ventilation hose
Clogged filters
If fuel filters or sieves on the intake side are clogged with dirt, the initial symptoms are as follows:
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. because a prefilter or the sieve filter in the fuel pump inlet is blocked, there is a risk of “dry running”. Dry running very quickly leads to damages in the pump system.
- Inadequate delivery rate
- Insufficient pressure
- Excessive operating noise from the fuel pump
- Engine misfires (due to fuel vapour locks) This can result in failure of the fuel pump and vehicle breakdown.
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. because a prefilter or the sieve filter in the fuel pump inlet is blocked, there is a risk of “dry running”. Dry running very quickly leads to damages in the pump system.
Fuel pumps in the E1F, E2T and E3T series are equipped with a built-in sieve filter on the intake side. This small “prefilter” provides protection against contamination. Tests on fuel pumps that were the subject of complaints have shown that this sieve filter is often clogged by dirt in the aspirated fuel.
When retrofitting an E1F, please note: For operation with diesel the sieve filter must be removed, as problems may occur at low temperatures due to the higher viscosity of diesel.
When retrofitting an E1F, please note: For operation with diesel the sieve filter must be removed, as problems may occur at low temperatures due to the higher viscosity of diesel.
Jammed pump system
If aspirated foreign bodies enter the fuel pump, the rotating parts of the pump system are often jammed. In most cases, the pump then fails immediately.
Foreign bodies get into the fuel pump when either the fuel filters or the sieves on the intake side are damaged or missing.
When working on the fuel system, in particular, there is a risk of foreign bodies entering the fuel tank.
Foreign bodies get into the fuel pump when either the fuel filters or the sieves on the intake side are damaged or missing.
When working on the fuel system, in particular, there is a risk of foreign bodies entering the fuel tank.
Pump system of a vane-type pump - Damage caused by foreign bodies The upper right-hand vane has been seriously damaged by foreign bodies. An undamaged vane is shown at the bottom right for the purpose of comparison.
1 Damaged vane
2 For comparison: Undamaged vane
1 Damaged vane
2 For comparison: Undamaged vane
Attention:
In-tank pumps often have a meshlike filter on the intake side. Therefore, during installation, take care not to damage the filter, and particularly any ribs in the filter.
In-tank pumps often have a meshlike filter on the intake side. Therefore, during installation, take care not to damage the filter, and particularly any ribs in the filter.
