Fuel cut-off in case of impact

PURPOSE

Its function is to prevent, following an accident, a fire caused by fuel leakage. To do this, all components pumping fuel from the tank are stopped during and after the impact.

They can only be reset by a manual action by the driver or the technician.

DESCRIPTION

The system consists solely of an inertia switch (1) which:

• detects the impact,
• cuts the electrical circuit.

It is fitted:

• on petrol engines, between terminal 1 of the fuel pump relay (236) and the +12 V supply,
• on diesel engines, between the + supply and the electric stop (or the coded solenoid valve if the vehicle has an electronic immobiliser).

OPERATION

During impact, the inertia switch ball leaves its seat and breaks the electrical connection.

On petrol engines, the + supply to the fuel pump relay (236) control circuit is cut. The pump and injectors are no longer electrically powered.

The petrol in the tank is therefore isolated.

On diesel engines, the + supply to the electric stop or the coded solenoid valve is cut.

The pump can no longer draw fuel and there is no high pressure. Any fire risk from high-pressure diesel spraying onto the engine is eliminated.

RESETTING AND OPERATION OF THE SWITCH

To reset the inertia switch, simply press it to return the ball to its seat.

IMPORTANT: for petrol engines, after resetting the cut-off switch, you MUST clear the ECU memory using the XR25 diagnostic tool. The injection ECU stores a fuel pump relay fault after the system has been shut off.