Loosen the big bolt at the center of the big spin-on filter. Move the plunger of the primer pump (either a loop like the dipstick handle or a knurled cover that pops up on it's own when you unscrew it). Fuel should leak out of the loose center bolt. Crank the engine with the starter. Fuel should leak out of the center bolt.

The stop lever is propped up at about a 75* angle when the engine is running. You push the lever down to about level to cut fuel and kill the engine from under the hood. If the lever is down for whatever reason, fuel will not get to the cylinders. It will stay down after you shut off the engine using the key switch until vacuum bleeds from the shut-off valve. When you turn the key to ON, it should instantaneously pop back to near vertical. If it's stuck down as you're cranking, pull it up, hold it that way and start the engine.

Sixto
95 S420
87 300SDL