TechASSIST: Fuel Delivery Modules / Fuel Feed Units

Fuel Delivery Modules and Feed Units

What is a Fuel Delivery Module

The fuel delivery module is essentially a combined in tank fuel pump and level sensor. The unit contains a motorised pump, pump controller and fuel level sensor. In this bulletin we'll look at what can go wrong, how to spot faults and offer advice on replacing components.

How does it work?

The fuel pump controller communicates with the vehicles ECU and operates the fuel pump to deliver fuel along fuel lines to the engine on demand. Fuel levels are also communicated to the ECU as the float attached to the fuel level sensor rises and falls.

Symptoms of a faulty module

  • Engine Sputtering at High Speed
  • Loss of Power While Accelerating
  • Sudden Loss of Power Driving Up Hill
  • Sudden Unexpected Acceleration
  • Failure to Start

Causes of failure

The most common causes of failure are contamination, overheating, general wear and tear from age. Motors and diaphragms are particularly prone to deterioration and age related failure. It is worth noting that in some cases the whole fuel delivery module may not need to be replaced. Replacement pumps and swirl tanks are also available from the ELTA range.

Fuel Delivery Module Components

Replacing Fuel Delivery Modules

Replacement is relatively simple but fitting errors are common. This is mostly due to the design of modern fuel tanks. Fuel tanks are now generally irregular in shape to make the most of the space within the vehicle design. They also often contain numerous other components (besides the fuel delivery module) inside the tank. When incorrectly aligned, this can cause obstruction to the fuel level sensor’s float causing incorrect or stuck tank indicator values.

To avoid such issues, we recommend that the following procedures are followed when fitting a new fuel delivery module:

1. When inserting the new fuel pump ensure that the sender float is able to move freely.

2. Ensure the pump is fully seated within the tank and then rotate clockwise until secure.

3. The top (flange) cover of the pump will usually have markings in the form of an arrow. Rotate the cover so that the arrow aligns the arrow marking on the fuel tank.

Incorrect Fuel Delivery Module Fitting

INCORRECT FITTING

Correct Fuel Delivery Module Fitting

CORRECT FITTING

Failure to carry out the correct fitting and alignment can cause obstruction of the sender float.