SOLVED, see below the photos.
I have a Derbi Manhattan (made in Spain) scooter with a 50cc two cycle engine. It is about 13 years old and last ridden about 4 years ago. Two years ago I tried to start it without success. I am finally getting around to look at it again. It has a separate oil reservoir and I'm not sure where it injects the oil (maybe the small black line entering photo 2 at around 3 o'clock--just below the white line?). There are two lines going to the carb that originate from a gizmo mounted directly to the bottom of the fuel tank. I cannot get gas to run from either line. I tried putting suction on both lines (one at a time) with no success.
Can anyone explain to me how this fuel system works? The fuel bowl on the carb is completely dry, as I expect it would be with no fuel coming from either line. The black and white lines run directly from the brass gizmo (shown in photos 3, 4, and 5) to the carburetor (shown in photos 1 and 2).
If nothing else, I will siphon out the gas (not a bad idea since it's four years old), take off the gizmo, and try to figure out what it is supposed to be doing.
As an aside, when the scooter was running four years ago (and always before that) it ran perfectly. Also, the inside of the carburetor is squeaky clean and two year ago the bike would fire and run on a couple shots of starting fluid. I have not tried that since, and figure there is no need attempting to start the scooter until I figure out the problem with the fuel delivery system.
My only guess is that maybe the gizmo is a vacuum diaphragm that works similarly to the OEM petcock on the Valkyrie???
The gizmo was a vacuum shut-off valve. I do not know why fuel did not flow when I initially applied suction to the white line. I removed the valve (spilling more gas than I meant to), looked at it (there was not much to see, but it was clean with no scum or residue), beat it against the garage door a couple of times, pulled a vacuum on the white line and the black line opened. Reinstalled, pulled a vacuum for several seconds to fill the carb bowl, and the scooter fired right up. Put fresh Stihl 50-1 pre-mix in the tank just in case the oil feed is slow or stopped. Once I notice the oil level drop, I'll fill up with straight gasoline.
