98 Oldsmobile Silhouette 3.4 SFI smell raw fuel after tuning off engine then fails to start because it's flooded?
The Fuel pressure regulator is the most likely cause.
It is the circular device most visible after you take of the plastic cover for the engine. It has a vacuum line that connects to the Throttle body or intake manifold.
What happens is the diaphragm in the fuel pressure regulator is leaking and allows raw fuel to leak through the vacuum line and into the manifold or throttle body.
if you replace the fuel pressure regulator it should fix the problem.