3232836 - 1040A fuel tank and components

CONSTRUCTION FEATURES

Immersed pump unit complete with fuel gauge sender unit

It mainly consists of:

  • a roller type electric pump
  • a fuel gauge sender unit
  • a fuel filter.
For EURO 3 versions,an O-Ring ensures a seal between pump cover and tank. Thus the immersed pump complete with fuel gauge sender unit assemblies are not interchangeable.

Electric fuel pump

The electric pump immersed in the fuel is the positive-displacement roller type with a permanent-magnet brush motor.The impeller (1) rotates, driven by the motor, creating volumes (2) which move from the inlet port (3) to the supply port (4).These volumes are defined by rollers (5) which, whilst the motor is rotating, adhere to the outer ring (6).The pump has two valves, one single-acting valve to prevent the fuel circuit from being drained (with the pump not working) and a second excess pressure valve (7) which recirculates the supply when the pressure exceeds 5 bar.

Multifunction valve

The multi-purpose valve has the following functions:

  • pressurizing the tank
  • retention
  • seal in the event of roll-over.
The multi-function valve is thermowelded and so cannot be replaced individually.

Pressurizing the tank

The tank is maintained at a pressure of 55-75 mbar by means of a fluorosilicone rubber valve, which rests on a sealing edge.The valve is supported by a stainless steel plate and counteracted by a spring.When the pressure in the tank exceeds the specified value, it overcomes the resistance of the spring and the valve is able to rise, allowing vapours to flow to the canister.When the pressure returns to the correct limits, the valve closes again.

Retention

Under particular driving conditions, a vacuum could be created in the tank because of:

  • temperature changes
  • fuel consumption.
In this case, the valve's function is to restore the pressure of the tank by allowing air in.A fault in this function could cause the engine to miss or stall, because of difficulties in supplying the fuel pump.This function is carried out by the 'goose beak' valve formed directly out of the fluorosilicone rubber.

Seal in the event of roll-over

The roll-over function prevents fuel from leaking from the tank if the vehicle overturns or is on a very steep slope.During normal driving of the vehicle (bends, acceleration, braking, etc.), the fuel is shaken up and may spill into the canister.The car's high roll-over sensitivity prevents this spillage.The roll-over closure angle is less than 33°.