Régulateur de pression de carburant alternatif défectueux

The regulator controlling pressure in a gaseous fuel system — liquefied petroleum gas or compressed natural gas — as distinct from the petrol system's own regulator. These are separate circuits with separate components, and the pressures involved are far higher, so this is not the same part under another name.

On these systems the regulator is also a vaporiser, which is the part worth knowing. It drops the pressure and lets the liquid boil into gas, and that expansion absorbs a great deal of heat — so it is plumbed into the engine coolant to stop it freezing. A coolant circulation fault therefore presents as a regulator fault, with icing on the body as the visible evidence, and the regulator itself in good order.

Its failures are pressure faults and leaks. A worn diaphragm or a seat contaminated by the oily residue these fuels carry gives unstable or incorrect pressure. Depressurise by the correct procedure before opening anything, and remember that most of these installations are aftermarket — components and routing may match no factory documentation, so trace the actual system and find the installer's own paperwork, which is often the only accurate reference.