Leak Test (LPG): Notes
WARNING: This page is about a different car, the 2000 Ford Pickup, 2000 Ford Econoline, and 2000 Ford Contour. However, it is still accessible from the selected car via links, so may be relevant.
NOTE:
After vehicle has soaked for several hours, a very slight natural gas smell may emanate from within the intake manifold and intake air system. This is normal, as the fuel injectors leak down from the fuel injection supply manifold to the intake manifold over several hours.