It seems the Fuel Pressure Regulators and fuel lines in many Sierra Cosworths are reaching end of life given a number of recent fuel related fires.

The diaphragm in the OEM regulator may fail as it ages and hardens. If you find fuel in the vacuum pipe connected to the regulator its an indication the regulator has failed. Another indication the regulator may have failed is the inability of the motor to idle whilst running rich.

Direct fitment after market regulators are available with both fixed pressure inserts and variable pressure inserts. Another option is to have the OEM regulator refurbished.