One of the components in the old OEM conversions done on Ford vehicles that seems to have caused Ford so much grief was the TeleflexGFI Compuvalve. This device is an combined propane fuel injection computer and metering valve and could be considered the "brains" of the Teleflex Gaseous Fuel Injection system. Because it is so tightly integrated in the operation of the OEM engine management computer, a Compuvalve failure could easily shut the entire vehicle down without any way of switching back to gasoline operation.
Current versions of TeleflexGFI's alternative fuel systems do not use the Compuvalve and fuel metering is done directly by the propane fuel injectors located at the inlet of each cylinder.
For those people who are interested in the construction of the GFI Compuvalve, Franz Hofmann very kindly provided the following photos to us during the forensic examination of a TeleflexGFI system.