2551018 - INTRODUCTION - FUEL TANK AND PIPES (Cargo trim level, Doblò trim level, BIPOWER)

The fuel supply system is divided into a low pressure circuit and a high pressure circuit.

The low pressure circuit consists of:

  • tank
  • auxiliary electric pump submerged in the tank
  • multi-purpose valve
  • diesel filter;
  • return manifold.

The high pressure circuit consists of:

  • Radialjet pressure pump (see 1060);
  • distribution manifold (see 1060);
  • injectors
1, Fuel tank2, Immersed pump unit complete with fuel gauge sender unit3, Fuel filler pipe4, Multi-purpose valve5, Diesel filter cartridge6, Pressure pump7, High pressure pipes8, Distribution manifold9, Injectors10, Injector recirculation11, Return (low pressure) manifold12, Pressure regulator13, Fuel temperature sensor14, Fuel pressure sensor15, Diesel heater16, Thermal switch17, Inertia switch.The diesel is drawn from the tank by means of a pre-supply electric pump operating at 12 V, which provides a sufficient flow rate to ensure the lubrication and cooling of the Radialjet pump as well.The diesel filter is mounted between the electric pump and Radialjet pump.The high-pressure hydraulic connections are made by means of steel pipes with an internal diameter of 2 mm and external diameter of 6 mm.The pump recirculation must be sent to the tank separately from the fuel injector recirculation which, after being collected in a single pipe, is also sent to the tank.
1, Injector2, Pressure pump3, Pressure regulator4, Fuel filter5, Fuel tank6, Immersed fuel pump7, Distribution manifold (rail)8, Fuel pressure sensor

CONSTRUCTION FEATURES

The fuel tank, with a capacity of about 60 litres, is made of a plastic material.It is fitted with a flexible filler and comprises the seating for fitting the fuel pump and fuel gauge sender unit.

CONSTRUCTION FEATURES

The electric pump immersed in the fuel is the positive-displacement roller type with a permanent-magnet brush motor.

OPERATTION

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.

OPERATTION

This valve is built into the fuel filler cap, and it carries out the following functions, depending on the pressure present in the tank:

  • it discharges to the outside any surplus pressure which is created inside the tank (safety function); the pressure acts on the plate (2) and, overcoming the load of the spring (1), allows the surplus vapours to be discharged to the outside.
  • it allows external air to flow into the tank when an excessive vacuum is created in the tank, following the consumption of fuel (ventilation function). In this case, when the vacuum exceeds the load of the spring (4), it moves the valve (3), allowing air to enter.