Fuel Pump Inertia Switch
What is it and what does it do?
This is a device that is fitted to Lotus Turbo cars which use a high flow / high pressure fuel pump. This switch is triggered when it senses the vehicle has had an accident or heavy impact.
It is normally in the closed position so that the fuel pump can be activated when the ignition is on. It is calibrated to sense a particular level of impact (like an accident) where it triggers and cuts the feed to the fuel pump to ensure the high pressure / flow fuel supply is not continued if the ignition is still in the 'on' position (likely in an accident).
It reduces the risk of any subsequent fire being fed with fuel until the tanks are empty (could be up to 16 gallons !) It can be reset if it has been triggered accidentally. (Lotus have two types - one has a visible plunger and the other rubber button)